You missed a lot of line items that accompany home ownership and hosting roommates. 

That scenario, a 4% loan with an origination fee, sounds like a regular bank loan and a mortgage broker.That may not be the end of the world but with regular bank rates, come regular bank requirements and delays.

I have purchased quick books online and find it very geared towards regular small business and not real estate.

As a plumbing contractor how I've learned that one of the best ways to meet another decent contractor is to go an acutal supply house (not homedepot) and see who the regulars are. 

For the most part, if one tenant were to leave the quad my regular income would be stressed, since I am only able to rent out 3, as I am required to live there or have the note called.

I know the one I went to is hosted every month and has gone digital.

As it increases the money supply, prices rise as in regular inflation.

Or perhaps just an option for hosts if they so choose. 

I feel bad for funds or investors that primarily rely on regular payments from performing notes.

An interesting article in the WSJ on the disaster that is befalling Airbnb hosts, both owners and sub-leasee's.