Re: Wet drywall and insulation
First, get the roof secured to keep the rain out completely, whether that is done with tarping or repair of the roof surface.
You're right to be concerned about mold and the integrity of the drywall. It is likely that you'll have to replace the ceiling at the very least because wet drywall is very heavy and it will sag between the joists. If the water is being directed down through the wall cavities, then you'll need to strip at least one side of the wall, the remaining side and exterior sides of walls will dry out with little to no problems.
I suffer from CDO ... Its like OCD, but in alphabetical order, LIKE IT SHOULD BE!!!