I had a leaky roof that caused half the bathroom ceiling to come down. The roof is now fixed. I know I have to remove the rest of the ceiling as well, and dry it out before replacing, and possibly do some mold remediation. My question is, what do I replace the ceiling with? Regular gypsum board or is there a special something that needs to go up since it is a bathroom? Steps would be appreciated. :) Thanks!
Do you want to have to replace it again if there's ever another leak? If yes, then use another inexpensive paper-and-gypsum-based product, such as drywall, green board, etc. If no, then use cementboard. Maybe overkill, but for a small bathroom the uncharge won't be more than $40 and that stuff can get wet till the cows come home and not complain about it! Once it's up, you can texture it, skim coat it, paint it, or whatever you were going to do to the drywall that you were considering.
Any answers to this question will be heavily opinion-based. Here's mine.
Assuming a good roof and adequate bathroom ventilation, there's no reason to use anything other than standard drywall, properly sealed and painted. An exception would be a very low ceiling over a shower that's often splashed.
Note that the use of most greenboard or moisture board on ceilings requires 12" OC joists according to manufacturer standards. They for the most part are not a good material for ceilings and in my opinion offer nothing that drywall doesn't.
Your materials for above shower are concrete board or regular drywall. Unless you are building an enclosed shower or sauna than I would stick with drywall.
For moisture purposes greenboard does not matter, in fact with minimal maintenance and prep drywall vs. concrete doesn't matter either. In bathrooms we have at least two generous coats of an oil based primer go on the walls and ceilings. This is far more effective at keeping out mold from drywall/whatever. Top that with a mold resistant paint and you would only have surface mold if you did a really poor job of ventilating.
So your answer is drywall, oil, oil, paint.