No, if that is what they are doing. The proper responsorial Psalm, from the day should be said or sung, however there are exceptions. Liturgical norms state the following: 
 
[T]he responsorial Psalm, ... should, as a rule, be taken from the Lectionary. It is preferable that the responsorial Psalm be sung … In order, however, that the people may be able to sing the Psalm response more readily… Psalms… chosen for the various seasons of the year… may be used in place of the text corresponding to the reading whenever the Psalm is sung. If the Psalm cannot be sung, then it should be recited…. There may [alternately] be sung either the Responsorial Gradual from the Graduale Romanum, or … Graduale Simplex…or an antiphon and Psalm from another collection … providing that they have been approved by the Conference of Bishops or the Diocesan Bishop. Songs or hymns may not be used in place of the Responsorial Psalm (GIRM # 61) 
 
As can be seen, an exception can be made for reasons stated to using the psalm for the day. In some parishes, the ability of the musicians and or the people to learn and use different responses each week varies a good bit. Thus pastoral provision permits the use of certain seasonal psalms and refrains. But, substituting hymns in place of the responsorial Psalm is not permitted and only texts approved by the Bishops are to be used. 
 
Thus it is possible to see how the words of the psalm that are sung may differ from what is in your prayer book, but only if the variant text is approved by the Bishops. 
 
For musicians, parishes or pastors to make unauthorized changes to the texts of the psalm is strictly prohibited. Most commonly the forbidden changes involve altering the text to be “inclusive.” But theologically, the “Man who walks not in the counsel of the wicked” etc., is often a reference to Christ, and altering the text loses the Messianic reference. Hence bad and unauthorized changes yield bad theology. It is rightly prohibited. 

The Catechism states regarding Homosexual orientation: Its psychological genesis remains largely unexplained (# 2357). Hence the Church has no official doctrine that would either affirm or deny your assertion.
 
The moral requirements for a person of same-sex attraction do not vary based on the origin of the orientation. Rather, “Basing itself on Sacred Scripture, which presents homosexual acts as acts of grave depravity, tradition has always declared that "homosexual acts are intrinsically disordered. They are contrary to the natural law. They close the sexual act to the gift of life. They do not proceed from a genuine affective and sexual complementarity. Under no circumstances can they be approved.” (Catechism # 2357).
 
It is not unlike a diabetic, who may be so for genetic reasons, or by acquiring the condition, (perhaps by overeating). The bottom line is the same; they must carefully regulate their diet. Thus, whatever the origin of homosexuality, the requirement is clear, one must embrace the life of celibacy that God enables.

There are details of the Christmas story in the modern imagination that come to us from sources other than Scripture, details which may or may not be accurate.
 
So, it is true we do not know the exact number of the Magi who came. Many presume the number three, since three gifts are mentioned: gold, frankincense and myrrh. But there may have been two Magi, four or more, we just don't know for sure.
 
Likewise, the modern imagination tends to bring the Magi to the creche the very night of Jesus’ Birth. Yet Scripture implies that their visit took place, likely, at a later time. This is because the text speaks of them finding Mary and the child in a house (Matt 2:11), not at the creche.
 
Thus, liturgically we distinguish the two events and emphasize as well in Epiphany the “manifestation” (which is what “Epiphany” means) of Christ to the Gentiles and the call of the nations to faith and worship of Christ.

Yes, and to add to your reflection, we also seem to move forward and backward in time during the Christmas cycle. The Feast of the Holy Family, celebrated on the Sunday between Christmas and New Years features a Gospel of Jesus at 12 years of age. And then at Epiphany, celebrated more than a week later, Jesus is back to being an infant. Further, we observe the Feast of the Holy Innocents on December 28, a terrible slaughter that took place after the visit of the Magi, and then we move backward in time to celebrate the feast of the Epiphany on the Sunday near January 6.
 
Some of these anomalies are explained by the fact that the liturgical year did not develop evenly over the centuries. The feasts of St. Stephen the Martyr, and St. John the Apostle are very ancient feasts on the Church’s calendar. The celebration of Christmas, and the feasts related to Christmas, developed in later centuries.
 
It surprises many of us moderns that the ancient Church did not focus a great deal on the birth of Christ. We are very sentimental about Christmas and the baby Jesus. But the early church focused primarily on the Paschal mystery of Jesus’ passion death and resurrection.
 
In later centuries the Christmas feast became more elevated. But the focus was still more theological than sentimental. Thus, It did not seem so alarming that the very day after Christmas, we were back to celebrating other saints such as St. Stephen and St. John.
 
Later, as a celebration of Christ's incarnation deepened, theologically and culturally, there was developed the octave of Christmas. But the Church did not feel free simply to move aside the feast of St. Stephen and St. John, which were very ancient.
 
As for the chronological whiplash of moving back and forth in time, within the Christmas feasts, we should recall that in the celebration of the Sacred Liturgy we access eternity, rather than merely chronological time. For God, all times and events are equally present, and we meet him there, rather than simply on our schedule.

The liturgical environment has stricter rules than Catholics are necessarily obliged to follow in their own homes. While it may be ideal that our homes perfectly reflect the liturgical cycle, practically speaking, many Catholics begin decorating earlier in the month of December.
 
As for celebrations on Church grounds, that is a matter of pastoral judgment. Frankly, most pastors are rather relaxed about this, understanding that cultural influences, even if less than ideal, can be respected out of regard for the legitimate wishes of people to celebrate conveniently.
 
You are encouraged to listen carefully to your Pastor’s teachings, and strive to keep Advent as much as possible. But it does seem that some leeway in these matters is acceptable.

The norms of the Roman Missal state that, While the Priest is receiving the Sacrament, the Communion Chant is begun, its purpose being to express the spiritual union of the communicants by means of the unity of their voices, to show gladness of heart, and to bring out more clearly the “communitarian” character of the procession to receive the Eucharist. The singing is prolonged for as long as the Sacrament is being administered to the faithful…. (GIRM # 86). The instructions also state: When the distribution of Communion is over, if appropriate, the Priest and faithful pray quietly for some time. If desired, a Psalm or other canticle of praise or a hymn may also be sung by the whole congregation. (# 88).
 
Note then the emphasis on the “communitarian” nature of this moment. And while private prayer is not wholly excluded, neither is it extolled as the main point or purpose to be pursued at the time of receiving Holy Communion.
 
The Sacred Liturgy is fundamentally a public and corporate act of worship of the whole Body of Christ together. It is not essentially a private devotion. The norms do permit a time after communion for silent prayer, if this seems appropriate. The length of such time and the use of this option will vary depending on the needs of the congregation and other factors.
 
Your concerns are understandable, but they need to be balanced with what the Church teaches us about what the Liturgy most fundamentally is. Consider that in the first Mass, at the Last Supper, the Apostles did not go off and have private conversations with Jesus. Rather, they experienced him corporately, and the Scripture says, that after partaking of the Sacrament, they “sang a hymn” (Mt 26:30). If we extend the first Mass to the foot of the Cross, there too, those that made it that far, stayed together and supported the Lord and each other.
 
Private prayer and Eucharistic devotion are to be encouraged, but, there is a context where this is best. Public prayer is also good and to be encouraged. It too has a context that should be respected for what it is.

You are correct. Modern and very helpful devices such as the enumeration of chapters and verses are not part of the original biblical text. These helpful conventions were added much later.
 
The setting of the biblical text into chapters occurred in the 13th century when the Catholic Archbishop of Canterbury, Stephen Langton assigned chapter numbers in order to make the reading of the Bible easier. The enumeration of the text into verses did not happen until 1551 when Robert Stephanus, a Protestant, former Catholic, classical scholar and also a printer, published the first such Bible in Paris.

As with any written text, some sophistication is necessary when reading the Scriptures. All or nothing approaches which hold that the Bible is to be read in an entirely literalist way, or that it is all merely symbolic, must be avoided. The more authentic question is, which texts are to be read and understood literally, and which texts employ metaphor, simile, hyperbole, or other literary techniques?
 
Thus, to cite your friend’s example, it would be strange to read Jesus literally when he says, “I am the door.” This would require us to think of Jesus as a large wooden plank, with a doorknob. It is reasonable to conclude that Jesus is speaking metaphorically when he says this, since the specific context of the saying, and the wider context of the overall Scriptures, in no way encourage us to think that Jesus spoke in a literalistic manner here.
 
When it comes to the Eucharist, however, there is a very different conclusion to be reasonably reached. When Jesus says over the bread, “this is my body,” and “this is my blood,” we are on good grounds to conclude that he is not speaking metaphorically, but literally. This is because the wider context of Scripture supplies, and insists, upon a literal interpretation.
 
In particular, Jesus insists in John 6 that the bread he gives is this true flesh for the life of the world. The Jewish people, listening to him that day, understand him to be speaking literally, and most of them scoff and murmur in protest. Though Jesus could have corrected their interpretation, and insisted he was only speaking metaphorically, he did nothing of the sort. Rather, he intensifies a literalist interpretation by insisting that they must eat his flesh, and drink his blood. Many, horrified at this, left him and would no longer walk in his company.
 
Thus, Jesus pays a rather high price, for a literal, not a metaphorical, understanding of the fact that Holy Communion is in fact a receiving of his true body and true blood.
 
St. Paul also teaches that Holy Communion is a partaking of the body and blood of Christ and goes on to insist that those who receive it unworthily, sin against the body of the Lord.
 
A final bit of contextual evidence is supplied by the fact that the early Church, as seen in the writings of the Fathers, universally understood these words in a literal way.
 
Hence we are on good ground and insisting, that the utterances of Jesus, “This is my body… This is my blood” are to be interpreted literally. This also illustrates the kind of sophistication necessary when approaching sacred Scripture.

No it is not so. Jesus actually multiplied the loaves and fishes. The “spin” given in the sermon is a rather tired and dated notion that developed in the 1970s. It has a seemingly clever insight with a moral imperative, that if we learn to share, there will always be enough.
 
But denying that a true and plainly described miracle took place is not respectful of the text. Jesus says plainly, they have no food (cf Matt 15:32). The Apostles observe the same and offer as evidence a mere five loaves and two fish. Further the texts are clear that it is from these five loaves and two fishes that Jesus feeds the multitude miraculously. The Apostles take and distribute the food from these very sources. There is no indication whatsoever that people started taking out other food that they had been hiding and learned to share.

The Catholic practice of reserving communion to fellow Catholics is fundamentally rooted in two things. First there is a norm of Scripture: A man ought to examine himself before he eats of the bread and drinks of the cup. For anyone who eats and drinks without recognizing the Body of the Lord eats and drinks judgment on himself (1 Cor 11:28-29).
 
For St. Paul, the issue is not only sin, (which might exclude some Catholics as well), but also, the need to “recognize the Body.” Yet a great majority of Protestants do not believe Holy Communion to be the Body of Christ, but only a symbol. Hence they cannot truly say the “amen” that is required to the acclamation, “The Body of Christ.” Thus, out of respect for both them and the Sacrament, we do not ask them to assent in faith to something which they regretfully do not believe.
 
A second reason for not sharing Communion is rooted in the fuller meaning of the Sacrament. In receiving Holy Communion, we do not merely speak of a personal communion of the believer with Jesus, but also of Communion with one another in the Church. But sadly, there are many things that divide Catholics and non-Catholics. In coming forward, one attests union with Jesus Christ, but also union with his Church, and all she teaches. Since this is also what Communion means, it is inappropriate for those who do not share this communion with us to come forward and signify what is not fully true, nor should we ask them to pronounce the “Amen” that affirms this community.
 
Thus, there is no rudeness intended by this practice of ours. Rather, there is a respectful, but regretful acceptance that others do not share our beliefs in certain significant matters.
 
As to dangers, note that St. Paul warns of incurring condemnation if we receive Communion either in serious sin or without discerning the Body. When we consider the meaning of our “Amen” at Communion, it is also sinful to solemnly affirm what may not in fact be believed.