He is not in a good health condition right now so I want to make sure I do this right if anyone can offer tips or where I should ask for help.

health and safety code violations?

I like to understand who the major employers are and I look specifically for health care, tech, government, military and Universities.

The futureWhere these meet and muddle the clarity is this:  you can't know or control the future, so even #1 is unknowable.In theory a loan that adjusts every 5 years is great if you're planning to sell the home in 2, but the present economic frailty is a good illustrator that we can't predict the next 3 months, much less the next 3-5 years.   

Tenants like this need to be put in their place early, if it is not a health or safety hazard don't touch it. 

If they aren't, it's either because of some sort of health issue or because the human isn't doing something right such as cleaning the box!

We not only lost our hard-earned money but on top of everything, our health suffered, I had several sleepless nights due to the stress and anxiety that this horrible experience created for my wife and me.After the buy-back was completed, I approached Maverick to at least help us with our losses by requesting us to give back ~$6000.

Seems to be a lot of health care systems in this area. 

@Erin T. the exact line in the updated ADU laws that @Dan Heuschele and @Eddie Torres is 65852.2(d)(2), which says "The local agency shall not deny an application for a permit to create an accessory dwelling unit due to the correction of nonconforming zoning conditions, building code violations, or unpermitted structures that do not present a threat to public health and safety and are not affected by the construction of the accessory dwelling unit."

And, to play this game it requires ongoing effort to stay on top of your debt, watching rates and keeping yourself in good financial health.....but can be well worth the effort especially since you are in the real estate arena watching the market anyway!