I decided to do a walk through on Fri, July 31, 2020 and found that they are growing marijuana inside a tent in the living room, have 6 cats 1 dog, 4-5 firearms in a closet with no lock-box, holes in the walls - some are obvious that they've been patched and others have not been patched, leaks under every sink that now are growing mold, 1 bathroom sink is completely molded underneath the sink to the point where the sink is slowly sinking in through the wood, and that they are not cleaning.

I own and manage my rental properties as well, however, I still have the option of managing other investors' properties carried underneath my partners Broker's license. 

We found hardwoods underneath the carpeting, so that was a nice bonus.

During the initial walk through the contractor did miss a few items: wood rot underneath the house, a leaking sink, a few minor cosmetic issues regarding the bathtub, a leaking water heater, and a few other items.

You need experience and knowledge in; soil suitability, EPA guidelines, Department of Transportation requirements for highway/road access, road development, zoning and permitting, accurate bidding, utility management, life/safety requirement and so forth.  

I'm using Behr latex based ceiling paint, but there are several layers underneath of unknown composition.The labor involved in removing the multiple layers of existing paint is such that is not a practical option as the unit is occupied.Thanks in advance for any tricks/tips.

A house that old likely has at least some asbestos, and things like soil contamination, abandoned septic tanks, unsuitable soil, etc. could all drive costs WAY up.Do you have financing and or an exit strategy for all possible contingencies?

Asbestos, soil contamination, lead paint, other epaFloor load, what uses can it handle.  

It states because there is less then 18 inches to access underneath the house, an inspector will not be able to provide a wood infestation report and therefore the seller will not be held responsible for any wood damage in the house.

Had a flood from the dishwasher which got water damage underneath the linoleum floor.