We must screen our tenant's thoughtfully and have a clear lease agreement.

It's an assignment agreement that's a side agrement between you and the assignee/buyer, and is separate from the regular TREC contract between you and the seller. 

Do we need a real estate attorney to review the purchase agreement and lease documents?

PURCHASE AND SALE AGREEMENT (PSA)

@Donald F.Talk to your CPA / Attorney as you want to make sure everything is by the book.Are you and your partner contributing the land into the JV agreement where the developer will build on?

He is swapping the planned materials, and HVAC machinery to lower costs without my agreement.

Now that he wants to change that agreement, he needs to read the contract and see what it says about termination.

I think my favorite option is to let him list it, then I could show him my Exclusive Agency Agreement and demand he pay me a hefty referral fee to make it stay quiet.

Obviously if this is expected, it needs to be in the signed lease agreement.

From a consumer's perspective it might seem unjust but that is the agreement you entered when you chose to purchase the nights at that property and should have done the right due diligence.