The problem is scarcity exacerbated by local governments dissuading investment in new supply or the investment in improving existing inventory. 

I contemplated being a realtor and I came across Rich Dad, Poor Dad which guided me to the sector of real estate that I was most interested in.

Of course if you want to switch to different license type, you have to go through the whole application process again, and pay applicable fees.I believe this is governed by the accessory dwelling unit ordinance which was revised recently. 

How likely is the local government to honor a 70 year old variance?

As I'm sure you know energy has never been an open market, every form of energy receives significant government support, and solar is no different in that regard. 

I understand this is some type of federal government assistance program for low income areas.

What's vastly different is the property tax, school zoning, and commuter costs.I am very new to RE investing, but my hunch tells me that if the main source of funding for schools in a given school district is the properties and not a commercial sector, this will eat into the potential appreciation.

Bonus points for more recession proof industries (health care, government jobs, education)Median income over $40k (your tenants need to be able to pay the rent)Average home price over $100kLow unemployment rateLow housing vacancy rateMarket with a strong affordability factorLandlord friendly  Those are just some examples. 

Without substantial government subsidies, tax breaks, etc. the numbers just don't work.There's a saying among RE investors who deal with large apartment complexes: "If you want a C-class property, build an A and wait 30 years."

If a tenant is receiving government assistance (Section 8, Abode, Vash, etc.) then they are NOT restricted to rent control.