Second, Texas also allows Texas homeowners to do cash-out refinance their primary residence.

Quote from @Marc Shin: I saw a video by Miles Golden and he said you change transfer your primary mortgage to a HELOC, and then you can pay all your bills out of the HELOC and pay off your mortgage in 3-12 years. 

My primary strategy is Fix and Flip, and I bring a DIY attitude to every project.

If maintaining cash flow is your primary objective, you might want to explore other options.

You should be able to claim the ENTIRE mortgage interest as they let you on primary homes.

Clearly, they failed in their primary responsibility to you as their layer of due diligence was a mere gossamer like patina.

Have the property taxes increased because this is an investment property and not a primary residence?

I am renting two units (1 basement and 1 side unit) in my primary residence.

Strategy 1: buy a duplex, live in one unit (for one year as a "primary residence) and rent out another unit as a short-term / mid-term rental on Airbnb.

They get a higher return since they are covering housing cost, have the $250k per spouse primary residence deduction in gains, is a savings account, higher leverage position, lower interest rate possible, will pay more premium for location, etc.House might be overpriced for REITs but not for home owners.