With the roof the other issue you have to consider is blow off.

You may be able to find 15% down but even that is VERY hard to get and with the changing lending climate could completely dry up.

Just click through the active listings and see how long they have been on the market, if they are mostly longer than yours, at least yours hasn't gone blow average yet.

Major dry rot/pest issues or perhaps knob and tube wiring would make me hesitant as well. 

I’d rather trust a professional with a moisture meter to see if it’s dry (just after or even during a heavy rain would make me feel better) before fixing the ceiling.

I called a company that an insurance had referred to do the drying .  

Additionally, you should probably instruct the PM to dry out the attic if you have with fans and / or a dehumidifier. 

And lets in all the humidity that was removed during the day.I once considered adding a duct and fan to blow air from the basement to the 2nd floor in summer, and from the 2nd floor to the basement in winter.

I’m hesitant because of mold, dry rot, etc. what should my frame of thought be on moving on these.

But hey…maybe you have an uneducated seller..there are plenty out there, *FSBOs cough cough* lol jk…sorta.This is common knowledge, but it does still blow my mind how much money some sellers will leave on the table for a cash offer instead of a financed offer..