In your original post you mentioned many things, and lot of scenarios, so if you are concerned about contingencies, protecting your interests, drawing up 1st or 2cd mortgages, etc.....that is why I suggested an attorney.

I would be more concerned about the parents' willingness to pay repairs when their kid has a party and wrecks the house.

Not a lawyer, but I would have some concerns if I wasn't licensed and was involving your buyer in the transaction with their POF/Preapproval. 

I'll be accompanying him from start to finish on an inspection.  

I am concerned that at least one of the 2 walls is load bearing and both have electrical outlets in the walls.  

His only concern is getting a reasonable rate of return that outperforms the market with a secured and collateralized cash flowing commercial property. 

Tell him your concerns, see where the breakdown in communication is, and figure out how to improve it going forward.

I prop at one of the big casinos out here.The issue with finding a reliable agent is indeed my main concern.  

I wasn't planning on extending onto that piece of land in question, but I'm concerned would be the word.

A salesman will not know this, his only concern is getting you to sign on the dotted line.