Talk to a good CPA and attorney (ones that own investment properties) and let them advise you on what to do regarding asset protection.

This will give you the best ROI and audit protection.

There are protections from “clerical errors” and you have correspondence proving the agreement was only through 2/2/20.

The mortgage is still in sellers name until some time in the future. 1)How do I or how am I properly protected if my Seller dies?

Part of that is for your own protection so you're not overleveraged.

Wasn’t clear from your post if grounding the outlets/protecting with GFCI was part of that bid...

Smokers are not a protected class.

If he tries pushing back, I would go to an attorney and let him know you're serious.In the future, you should have some rules laid down for roommates to ensure their peace is protected and to give them tools to work things out when a particular roommate gets out of line.

I have a few like that.Definitely for asset protection use an LLC for the asset and ensure with your lawyer that the LLC isn't regarded as a pass through entity to your personal name. 

I like to protect myself as much as possible.