Unfortunately it's the squeaky wheel that gets the grease.

Replacing all light fixtures, faucets, doors, door knobs, ceiling fans, every inch of wall was repainted, all moulding from brown to white, new laminate flooring through the whole first floor and vinyl in the bathrooms, repainted the deck, and really landscaped outside, as well as a brand new porch.

They may not cover local issues, but are great to get the wheels turning in where to  look next to grow.

Hopefully if you thought you were within inches of the starting line you now see you should take a little more time to look around and gain some more knowledge.  

Now the short answer is, unless you clean every square inch the property is still contaminated.

If you have the money, i would do that plus add a metal z channel going opposite direction of the joists ( screwed on top of the existing plaster ) and then add another layer of drywall. the Z channel leaves a space that helps in sound transmission. the problem is the sound is transmitted through the existing floor joists too, so just the insulation will not do it because the joists are still against the ceiling. this is something similar, but in this picture they used clips in combination to hold off hat channel from the existing ceiling which will lower your ceiling about another inch. 

I have been involved in releasing government liens on many occasions to complete sales but this scenario is outside of my wheel house.

Professionals drill (two feet or the longest masonry bit available) into the hole every 24 inches around the exterior and interior (if the basement is not finished) perimeter of the building and spray the chemical into the hole.After you have sprayed the chemical in the hole patch the hole with cement so the rain doesn't flush the chemical out.

At least partially, but the bath could have a roll-in shower, handles, sans the turn radios for a wheel chair unless I open the door to the living room. 

They have great river rafting, 4 wheeling, hiking, biking, etc.