Its more so they can communicate concerns or issues with me if there are any as well as not be held responsible for potential damage that was not caused by them.Is this common practice? 

Private investors or lenders to flippers is common practice as is the 50/50 split. 

Though I don't think NOI in residential has any practical use in valuations or towards other financial instrument applications, it definitely is helpful to analyze synergies forecast in OPEX when you get multiple properties. 

1) They will let the lease slip into a month to month practically forever.2) There is no incentive to seeking rent-raises unless the staff has financial incentives to do so.3) The alternative is a vacancy - costing the Landlord / Owner thousands of dollars! 

Motel owners leaving at the property is common practice.

Practice your pitch!

Seeing how little of principal is paid off in the beginning of the loan cycle, my urge so far has been to throw what I have as extra payments chipping away at that mountain, but I’ve been also thinking lately if that’s a wise practice.

I don't think it'd be practical for both the main house and the ADU to share the driveway.

Don't let emotions get in the way of making practical decisions.

If you hit all the best practices checkmarks i.e. maximizing the space, renovated, great outdoor space, pro photos, priced competitively, you will do fine!