Many non Catholics have some really common questions
Why to Catholics worship Mary?
Catholics do not worship Mary, we do however in imitation of her Son Jesus we respect her the way He would have respected her, above all other women. Jesus obeyed the 4th commandment, Honor your father and mother. He would have had more respect for her than any other woman.
Why do Catholics have to confess their serious sins to a priest?
Well it is not so much that Catholics have to, but rather they get to confess their sins to a priest who can forgive sins from apostolic succession. In John 20:19 Jesus gave the apostles the ability to forgive sins.
Why do Catholics pray to saints?
Actually we do not pray to saints but rather ask them to pray for us. We have friends in high places.