If they spring something on you at the closing table, run, don't walk, away.

EB is great source of renters with solid incomes and I have found that our EB renters seem to prefer our listings in Groton being closer to EB and in some cases walking distance.

so after reading all the posts, it sounds like his best bet is just to move on and walk away finding another place maybe coming back in future to keep contact with that person if he really wants that location… Correct me if I’m wrong, but my analysis from all this is that hiring a squatter would only be applicable in situations where the person who is occupying the residence never had a lease or contract therefore it is a rare circumstance where it would be a viable option. 

On the rehab I would maybe pay a GC to walk a few properties with you so you can learn and understand the costs.

You can lower the price.The buyer can pay the extra $9k in cash, if they have it.The buyer can walk away with their earnest money and you can lower the price $9k for the next buyer or require them to bring $9k in cash. 

After the walk-through, they will see if the tenant has interest in renting, and if yes, they would sent them the questionnaire so they, and I quote, "save the tenant the $60 for application fee", in which within the questions it would be things such as, if they have pets, yearly income, cosigners, if credit score is above a certain number, etc.

After going this route, and further analyzing the property that I was looking at, with the higher interest rate, HOA fees, non-investor-friendly co-op rental policies, I walked away.

This is basically giving the tenant the right to just walk out and not be responsible for a lease they signed. 

Walk the props, It will take 15 minutes to understand pricing, 

Also, walk the area..