Here are the answers to your questions:
1. Catholic Mass is the weekly ritual service in the Catholic Church where Communion is taken. It commemorates Jesus' death and sacrifice.
2. The building monks live in is called a monastery.
3. One example of power the Catholic Church had was that it could excommunicate people, preventing them from receiving sacraments and going to heaven.
4. One of the Catholic reform movements was the Friars, who were wandering preachers in the 1200s that encouraged further reform and lived among common people to preach.