I could answer your questions, but I suspect there are many more holes in your education that you aren't even aware of. 

As Matt Devincenzo suspected, the county website was showing the 1985 Vs the Title that shows 1962.

I suspect that we are going to be discussing this topic on the forums for the next couple of years, particularly in markets where rents have not increased much (but the magnitude you mention above is extreme). 

At the same time, I for one know that I overbought both, as I suspect most people did. 

I suspect a spouse or dependent would fall under IRS self rental rules. 

I suspect to this day virtually all of the "ADUs" in City Heights are not fully permitted.   

I like Dave Ramsey, and I follow many of his recommendations very carefully in my personal life.I suspect the easiest explanation for the occasional disparaging remarks about him here and elsewhere, @Brian Ellis, is that there's a lot of wishful thinking in REI. 

I suspect that the industry trends are being driven by a combination of factors that are sometimes contradictory: (1) gas prices, (2) pent up travel demand & (3) the traveller's perceived personal risk to Covid. 

However if you plan to keep it as part of your buy-and-hold strategy and you suspect that rates are NOT gonna get lower anytime soon, makes a lot of sense to do this.

I have no experience in single family but I suspect it may be a bit of a different animal than multi (higher turnover, lower credit tenants, etc).