I didn’t know this and the Indianapolis heat caused the flooring to swell and buckle.

One bedroom/closet the cigarett smell is strong especially when heat rises and the smell is trapped in the carpet. 

I have a property under contract that I am penciling out my thoughts for the SOW before I bring over contractors and I originally thought I would have to remove it and install a new ac/furnace but my interior designer...

Even brand new HWF will have a little noise, which will also vary through the seasons with heating and humidity.The squeeeek-no-more screws work when you don't have access from underneeth for example on the second floor. 

I believe you live in NC which also has some cities with similarly priced Multifamilies.In fact, I know investors who live in Miami, Florida and Ft Lauderdale who are investing in North Carolina, just because the numbers are better.What I am getting at is that in order to bud an empire fast, you will want to pick 1 city and closer to home the better.It would have to have affordable multifamilies also.

The building provides heat/coolant.

Nothing on the West Coast will prepare you for Milwaukee winters and heating bills. 

Roof, HVAC, plumbing, electrical, kitchen, bath, walls, floors, foundation, ceilings, etc.I have found that what costs is when the entire house needs to be replumbed or  there is no heating and air, or the roof is bad, or the floors are falling in,  rather than the cost for a bedroom rehab.Then again, I buy foreclosures and they tend to be worse than regular housing. 

The current home we are looking at is a single family on 11.5 pastured acres with a 5 stall heated horse barn. 

My wife and I are thinking about purchasing an older home that is very up to date with the exception of a boiler heating system.