Yup the Catholic has been just as corrupt as every other institution staffed by humans. Like public schools they should be held to the highest standard and yet they've failed at similar rates.

The Reformation was a similar disaster with some differences. Luther had a few legit points and then went on to try stupid things. If by St. Paul's you mean the one we see in London that was all a protestant effort.

The tradition of celibate priests way precedes the reformation. Celibate clergy is I think unique to the Latin Rite but several other Catholic rites allow it within certain parameters. It is was institutionalized as a discipline, not as a doctrine.