You will need to take Marriage Prep-Courses to determine if you are compatiable with each other...
The Catholic parties will need recent copies of their Baptismal Certificates
Sometime before the wedding the priest will interview the couple who should bring their documents along. This is called the PMI, the "Pre-Marital Investigation", along with the information about what parish one belongs to, the Baptism information and whether one is free to marry in the Church. The priest will ask questions about each parties full consent to the marriage and his or her commitment to a permanent relationship. He will also ask about children. If it is to be recognized as valid in the Catholic Church, the marriage cannot exclude the possibility of children.
The final question is about the willingness and cooperation of the couple to the values of the Church about procreation.
There are other rules as well. Some don't allow certain styles of dresses, others don't want you throwing any birdseed or confetti, etc