Be aware if their payment is clearly labeled "for rent only" or similar, and in that case, only apply it to rent. 

There are things you need to be aware of prior to going down that path, though

Ethically for sure, but I'm not aware of a legal responsibility.

As I'm sure you're well aware, the small multifamily space in metro ATL is competitive despite current interest rates. 

They pay rent before the due date, clean the property after every client, and if something breaks they usually repair it before I'm aware because their clients will give them bad ratings.

Many people choose NOT to have this, because the administrator will then vet every investment you make to ensure you do not invalidate your IRA.Invalidating your IRA means that you've done a prohibited transaction and the entire account is then deemed as distributed to you.If you don't want checkbook control, then I recommend a plan administrator such as Equity Trust - www.trustetc.comIf you are sure that you're aware of all the rules around prohibited transactions and disqualified people (who you can and can't do business with), then a plan administrator like Sense Financial would be a good place to start talking.  

Are there other players in this field that I should be aware of and consider talking to before making a final decision?

You will want to consult with a lawyer.In regards to your last two questions here's some background on what makes a contract valid and enforceable:Offer: A promise to do or not do something within a certain time period Acceptance: A clear and direct statement that all terms and responsibilities are accepted Consideration: A legal and adequate inducement given in exchange for the promise Capacity: The parties to the contract must have the legal capacity and competency to contract Awareness: A party must be aware of the contract Legality: The contract must be legal in the jurisdiction it will be operating in***Not legal advice*** Steps I would take: -Review contract in detail to understand each counterparties responsibilities (if you are not aware)- Email a copy of the lease to each of the tenants listed on the lease and reiterate lease expectations for termination notice, rent payment etc. - If the lease was signed via Docusign (other esign may have same ability) - you can go to the envelope, go to history and view the IP addresses for each action taken.

So be aware of that.

Any legal issues I should be aware of in this situation?