Now claiming it wasn't full when they arrived.  

This also helps in case you get a real jerk who claims that fridge is theirs...then you have paperwork they signed stating it is yours.In my latest rental, it just so happened to come with washer and dryer.

They claim the big issue is that the apartment does not have its own legal address and is not listed in the property appraiser records in my county. 

Even so, I've only seen cases where the plaintiff or heirs claim to have paid the mortgage in full, none where they were attempting to extinguish known existing debt.  

Hello, I live in Florida and I know about Unclaimed excess tax deed sale proceeds, is it legal to have a company where have my attorney draw up an agreement between me and the person who has claim to this excess money to where I tell them about this money the have claim to for a fee?

The reason being that good GCs have insurance requirements a sub must meet in order to protect themselves from claims arising from a subcontractor. 

He claims people will pay $1000 in rent, I'm thinking more around $850 to be safe.

You would have to keep their deposit and take them to small claims court to recoup the damages.

Transfer the deed using a Quit Claim.

They have to sell a lot of policies in order to be whole if they just have one $1MM claim out of thousands.