And then decide with your partner what your ceiling is for this to be a good deal.And always prepare for the worst, and hope for the best.

We had a similar issue with a much older home & yours may also be an easy fix if you have it assessed correctly.The poorly fitted gutter/flashing interface on our upper roof (to the right of the galvanized stack we removed) finally let go & a very small finger sized hole let in the moisture.The fix could have been a simple bandaid but I decided to replace the 1987 roof instead. (24 square on a Sunday with 8 guys helping $5k).But it then required the 'surgical' removal of one section of moldy kitchen ceiling drywall.

I did find 1 good contractor in all of this.  2 brothers that did an AWESOME JOB removing all the wallpaper, skim coating the walls, fixing issues in the ceiling drywall and hanging some new drywall.  

See in a single story homes all the wiring for the most part (except vaulted ceilings) is accessible by attic, therefore not much drywall needs to be removed Vise-versa two story homes require a lot of drywall to be removed. 

What I meant was you set your ceiling based on your numbers.  

I'd not ever do split utilities, never, under any circumstances as you can get into utility regulations as a utility provider.Not mentioned, the renovation costs, but you know that, especially in older buildings, ceiling joists are not sufficient for floor joists, even if the attic is floored, it may not pass standards as a living space.

I heard in one of the podcast to use CAN lights instead of ceiling fans in order to avoid maintenance later.

cool i'm in a similar boat albeit here on the west coast. hopefully its not under ur own roof u come home to as thats when its at its worsts - 24/7 and obviously not worth it once they default AND/OR breach. tenants too often dont seem to realize not paying and/or not keeping any unlawful (ie, prohibited) activity at bay IS as serious as if the landlord were to suddenly, permanently shut off the water/electric/gas etc or lift the ceiling off their rental.

You might have a drop ceiling and don't know what's above, until you tear it out. 

The contractors have removed all the drywall and the ceiling.