What is the proper way to notify the other two that they have not been selected and their app fee will not be refunded.

You can’t determine exact loan balances but you can usually get close, assuming they’re not in default.

The loan balance is currently $93,553, but no cash flow.

We did a proper screening just like we have with all our other tenants but these tenants completely did a 180 on us the moment the received the rental. 

Then, when you find a buyer, you are assigning your rights in your personal contract to that buyer in exchange for a fee.First, if you were working for me as a real estate agent where I was your managing broker, I have an obligation from the state to supervise your real estate activities and if I don't do that properly I can be reprimanded and/or fined and/or possibly lose my license.

A properly designed permanent life insurance policy is the underlying asset. 

If I created an LLP, I believe I could have the LLC (or S corp) be a member but I’m not sure if I can do that with an LLC, and I am unsure what the best structure may be to balance protection and taxes.

Have you filed a proper eviction:ejectment action?

That makes it easy to see their balances with no additional work on my part and separates their money from mine.

Alternatively, depending on the nature of your financial sophistication/willingness/balance sheet, you could also look into investing through syndications, JVs and/or partnerships.