When I'm in a SFR, I house hack by renting out the additional rooms (albeit I'm single). 

We will be purchasing another long term rental (single family) before the end of the year and plan to BRRRR properties until level 1 of passive income is reached (7-8 years/10+ properties).

Someone could be worth 50 million but if they have no guarantee or a single entity remote LLC it is worthless.You could have all that other stuff and they could simply walk away and keep running other locations of their businesses.If they are a large corporation you want to see if they are credit rated and then if investment grade BBB- or not.

(not so important but if they only require 15% down on a single family home that is usually a good sign that you are working with a flexible lender) Can I change title to my LLC?

Single Family Home. 

The plan is to sell my single family and buy a 3 or 4 flat.

I have a sale leaseback deal with a single tenant that will sign a ten year lease.

I own a rental property (a single family house) on a street where they're building a large "HUD 221(d)(4)" multifamily housing development across the street from the house. 

In addition, I'd like to either house hack my first single family house  or owner occupy a multi family (under 4 units) as I progress in my self mastery, personal finance and real estate education.

It’s just part of the single family market.