As your question suggests, exactly how we address Jesus will vary in certain contexts. Perhaps it is most important to distinguish at the outset that “Christ,” is not part of Jesus’ proper name, but rather, it is his title. In this sense, it sometimes helps to put the definite article “the” in front of Christ, saying, “Jesus the Christ,” to remind us that “Christ” is not his surname. Jesus is “the Christ,” Which means, "the anointed one" and translates the Hebrew word “Messiah.” 
 
His proper name, "Jesus" means, in Hebrew, “God saves.” To put all of this together in English, his name and title might be rendered “Anointed Lord and Savior.” 
 
While it is certainly fine for us to call him simply by his proper name, “Jesus,” in the formal liturgy of the Church we often speak of him more fully, such as, “Christ our Lord,” or “Our Lord Jesus Christ,” and so forth. 
 
All this said, it must be added that there are over 100 titles of Jesus, and ways of referring to him in the Scriptures which can also be appropriate ways of referring to him in certain circumstances. For example he is called: Alpha and Omega, Author and Finisher of our faith, Son of David, Son of Man, Good Shepherd, Emanuel, I AM, King of Israel, the Way the Truth and the Life, Light of the World, Redeemer, Teacher, Rabbi, Son of God, Son of Mary, True Vine, and so forth. There are more than 100 other such titles. 
 
Thus, we do well to remember that the magnificent truth of Jesus Christ, our Lord, often requires us to speak of him in many ways, pondering his glory from many different perspectives through these titles.

Let me state at the outset that I am not a civil lawyer. But let us suppose that there are legitimate laws in place that forbid purchasing and carrying certain items across state lines. Presuming such laws do exist, they ought not to be violated. This would be true even if we suppose that such laws are more likely aimed at large distributors, rather than private citizens. Unless that exception is explicitly indicated in the law or overruled by other constitutional rights, we ought not to simply consider ourselves exempt. 
 
It is a general norm for Catholics that we should obey all just laws enacted by civil authorities if they do not violate God's laws. If such laws displease us, we ought to have recourse, through the political process, to change them, rather than simply ignore them. 
 
If a Catholic knowingly violates just civil laws such as this, the gravity of such a sin varies, based on the frequency, purpose and amount of items purchased. If one were to simply purchase a small number of items, more as a convenience, the gravity of such sin would be rather light. However, if one were to repeatedly purchase a large amount of items, especially if they were going to resell them, this would be a much more egregious violation of civil law, and also bring with it a more significant gravity in violation of moral law related to the 4th Commandment.