. - Of course, you may need a Property Management Company to handle each rental when you move again.

Your property management company can help once you own the property but up until then you need someone good on your side!!! 

Has anyone used the company BNB Leverage to help with the airbnb arbitrage strategy?

This will be some management company, right?

Not sure if that is still legal or even translates in today's world of everything online but seemed like a good screening tool to me at the time. 

In Columbus, you can still find the 1% rule and there's amazing appreciation potential due to how much population growth, job growth, and companies moving/developing there (recently Anduril just announced another 4,000 jobs coming to Columbus Ohio on top of Intel, Google, Amazon, FB, Nationwide, Ohio State University, etc.).

Their return is better than most note companies.  

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.

And never being “at risk” is it even sufficient to legally bind a seller?  

Will they "check themselves" from bad behavior when they see a professional company with professional services, legally reviewed lease, etc. managing their day-to-day?