This person has agreed to sell to you for X price on/by Y date and you both have legal remedies if one or the other party doesn't follow through. 

This could be a long term remedy if you have to bring extra cash to close to then try to subdivide the lot, sell the additional parcel, and recoup some of your investment.

To make matters more infuriating, the requests from the tenant was one day after the 'turn' which was a signifant expense and should have remedied all of these issues.             

Some will insure you if you remediate the problem without doing a full rewire.

If it doesn't sell for a long time, they'll know they have a real problem on their hands and will start dropping the price.I've run into the pee problem many times (I'm working on one now) and have done a lot of remediation research.  

These are proven to be effective and are also certified by mold remediation companies and industrial hygienists.3.

The occupants of my house were locked out Feb 5th, 2019 and I am still trying to fix all the damage, mold remediation, etc.

When you're trading and you both have agreed on price, you are expected to close the transaction unless something comes up during due diligence that cannot be remedied directly or by a re-price.

After one year, you'll know most of the problems and have them remediated. 

Does anyone know about grant money available to owners of contaminated property used for testing a remediation?