The big worries are being able to convert those Rentals to Tenant owned homes.  

However, he converted the house into 2 units(2/1 and a 1/1).

Without further info the home looks like a huge old Victorian home that was converted into a multi fam (I could be wrong).

They have owned it almost 30 years and their accountant is recommending converting to LLC first and me purchasing their shares to reduce their tax burden.

Can you convert the garage into living space?

Since you've converted your primary residence into a rental property and then again to a primary residence, your intent behind the exchange could be questioned by the IRS.

Truck broken into, shoes stolen off porch, license plates stolen, catalytic converter stolen.

@Justin Mast north of you on the coast a couple has converted an RV park to a tiny house and RV place - they of course have amenities but I think you could spin it for a more rustic or eco friendly experience.https://tinytranquility.com/Or next level...http://minam-lodge.com/about/lodge/

The home is a 4 bed 2 bath single family that was converted into a Duplex, I have been wondering whether to keep the property as a multi family or convert it back to a single family.

The place has potential to be converted from SFH to duplex.