In terms of value, I am getting a bargain price compared to the flavors of the month, i.e.

In 1031 world there is no distinction made between financing only on property use. 

Perhaps I should have drawn a distinction between training and education.  

How much you will qualify for and where they make the distinction between residential and commercial mortgages.

But here's the important distinction: under my scenario, the author in year 10 would make $110k in cash flow and cash reserves would be higher than in year 9 by $10k. 

The ADU / MIL distinction is important for your rehab costs too, as an ADU will require a full 8-12 week permit review, and require separate heat, a separate electrical panel, and a separate hot water heater.

If I only have 2-3 houses at any given time, is there a distinct advantage (tax or liability) to holding the properties in company rather than my own name?

An investor that just holds rental property for the production of rental income is probably not engaged in a trade or business and would not qualify for some of the business deductions.There are special nonbusiness deductions allowed for investors that hold rental property.When discussing possible tax deductions it is important to keep this distinction in mind.

. , I think you made an important distinction - all inside and outside pets.I hate to throw a monkey wrench into things, but make sure they do not have Emotional Support Animals.

Keep in mind, South Florida has some VERY distinct neighborhoods that are quite different.