If so, another reason to use a RE atty because of different state laws.

Does that seem reasonable ? 

There’s a reason the government specifically calls out “ rent to own “ in the Dodd frank bill a “ predatory lending practice” Save yourself a huge headache and move along with someone else

Lots of people that own and operate house flipping business opt to structure either an S Corp or LLC taxed as an S Corp, but you have considerations like drawing a "reasonable salary", self-employment tax, etc. 

You have not needed a LLC for 5 years and there is no reason to think you need one now.

If he gets a judgement against him for any reason, a lien could and most likely would be attached to 'your' property.There is also legacy risk. 

I don't see any reason why you should not use it for the whole thing since Quickbooks is capable of tracking the things you mentioned.  

The reason most houses built today have forced hot air is because you can use the same ducts for air conditioning so it normally ends up cheaper.

The reason is many people want to pay cash for everything or take on little to no debt.

You could visit them for some other reason and ask to use their restroom, sometimes works!