I'm hoping I can get some recommendations on good readings or pod casts on the two topics: (I am more concentrating on the BRRRR method) I'm having a hard time understanding the benefits between buying a house cash, or using a loan/mortgage.

One consolation prize you may benefit from is that the AZ rental demand is very high and rents are up.

And that would certainly leave you in your current property long enough to get the tax free benefit of the primary residence exclusion.

Following for personal benefit as I am in a very similar position.

Was it buried in the part of them avoiding you, not returning calls, canceling meetings, and giving the appraiser trouble, all to their benefit and your detriment? 

I know rents are always going up, it will appreciate in the long run, there's tax benefits and there is definately room for potential value-add.

Is there a benefit in having the properties mortgaged with conventional financing and then going to a commercial lender for a blanket loan?

You will still benefit from having a paid off house (aside from the HELOC). 

I guess the upside is this young lady seems to be honest and could benefit from an ESA, I am highly annoyed by people who do not have the need and try to lie their way in with fake online registrations but this seems valid.

If you don't need the additional income, looking to generate long term wealth, tax sheltering benefits, etc buying for appreciation may come more into play.