Can any person be a sponsor or Godparent?

Is it ok to have my brother, who was baptized Catholic but was never confirmed, be a Godparent for my son’s baptism? Can an un-confirmed Catholic be a Christian witness and stand in place of one of the Godparents for baptism? Is it permitted to have my sister in law who is a fully initiated Catholic, but who was divorced and remarried outside the Church, be a sponsor for my daughter’s Confirmation? Is it ok for my fully initiated Catholic aunt, who doesn’t go to Mass, to be the Godmother of my newborn daughter?
 
The short answer to all four questions is no. When you take on the role of a Godparent you are accepting the responsibility of leading a soul to heaven, which is not an easy task to say the least. The requirements for Godparents and sponsors may seem confusing and hard to follow, but in reality are in place because the roles of sponsors and Godparents are to lead by word and example the one they are sponsoring to the absolute truth of Jesus Christ and be saved for heaven. The Code of Canon Law specifies the requirements for Godparents and sponsors:
 
To be permitted to take on the function of sponsor a person must:
 
1.  be designated by the one to be baptized, by the parents or the person who takes their place, or in their absence by the pastor or minister and have the aptitude and intention of fulfilling this function;
2.  have completed the 16th year of age, unless the diocesan bishop has established another age, or the pastor or minister has granted an exception for a just cause;
3.  be a Catholic who has been baptized, confirmed and has already received the most holy sacrament of the Eucharist and who leads a life of faith in keeping with the function to be taken on; (this includes participating in Mass on Sunday and living a Catholic life of faith-believing and living the Nicene Creed.);
4.  not be bound by any canonical penalty legitimately imposed or declared (like being divorced and remarried outside the Church without an annulment);
5  not be the father or mother of the one to be baptized.(CIC874).