I believe when he was about 22 years old
You have it backwards. Saint Patrick's Day was named after Saint Patrick. March 15 is the Catholic feast day of Saint Patrick.
Saint Patrick escaped slavery by fleeing from his captors and traveling hundreds of miles on foot to reach a port where he could find a ship back to Britain. He spent several years gathering resources and planning his escape before successfully returning home.
To convert every person in Ireland to christianity.
Saint Patrick was a man (or saint) who was taken from his native home in Wales by Irish (Celtic) raiders. After six years he was able to escape and went back home to his family. There is no direct connection between St. Patrick and the Church, but he became the Patron Saint of Ireland. in other stories though, it is said that he received a vision from God, and was shown how to escape from Ireland. It's also said, that he drove out snakes from Ireland. Either legends always say, that he is indeed, the patron saint of Ireland.
No, Saint Patrick was not a thief.
Saint Patrick was not married.
He was told to escape his slavery and go to the coast where a ship would be waiting to return him to Britain.
When Patrick was 16 years old he was taken as a slave to Ireland and forced to work as a shepherd until he managed to escape 6 years later.
Saint Patrick is buried in Down Patrick, Northern Ireland
No, Saint Patrick is Saint Patrick and not known by another saint's name. His birth name, however, was Maewyn Succat.
Saint Patrick is the patron saint of Ireland.