If you have a loan, you may wish to look into due-on-transfer clauses.

What loan size and loan to value?

Meeting a 20% down payment to avoid PMI seems manageable, although would take a big chunk of my liquid net worth, and I prefer this route over using an FHA loan.

Stairs are the only way to get in, no grab rails in the bathroom, ramps that are too steep, etc.From what I've read, all commercial businesses/buildings (including ones before the ADA was passed) have to comply with the rules, unless it would be outrageously tough to fix (like installing an elevator in an already built building).Are all these local business just not complying and taking the risk, or am I missing something? 

@James JeffersonHi James,To buy out the property you need to probably apply for a loan through any lender.  

How much will be the interest rate, and terms of the loan. 

If it is someone you know you can give them a straight return as if its a loan - can provide a lower interest rate to provide upside - it really depends on the lender and what are they concerned with and what is their risk profile. 

@Summer Shelton yes, FHA loans do allow this but make sure you speak with your lender about some of the trip ups from these loans.  

If you close with a conventional loan, it will need to be in your personal name.

Job included inside work of leveling floors, installing flooring, paint walls, kitchen cabinets, etc in both units, as well as lay a new driveway, fence the back yard, provide attic fans, and install electric to the crawlspace to add lights and a sump pump.