I would contact your local real estate board and see what answers you can get from them and also call a local trusted realtor. 

Yeah... honestly, you sound like you are way over the top and as my kids would say, "you are extra".

I'm on board with the others.

Ideally, you'll want to see average 90% occupancy across the board, otherwise you'll be relegated to regional bank and credit union lenders that require (i) recourse, (ii) deposit requirements at close, (iii) slightly higher rates, (iv) lower amortization, and (v) less interest only [if cash flow is a priority for you]. 

His wife who is in college for a degree that will lead to a great job with great pay when she graduates in June, now has full rent to pay, plus the cost of raising 6 kids by herself. 

I’m beginning my journey into real estate investing with the goal like many of you of generating passive income and discovering financial freedom without having to rely on a “day-job” for much longer, so I can travel more and spend more time with my young kids/family.

Look on the California State Contractors Board site at the various options.

In the past basic zoning pretty much allowed you to rent a house to 2 unrelated people (family/kids obviously don't count as they are related to the adult(s). 

Your spouse, partner, friends, or family are not on board with real estate investing.

With three new kids, the last thing you have time for is managing a decent sized renovation.