I just don't want someone coming after my personal residence if the bottom falls out of the market.

Suggest you find someone who can set up a trust for probate etc and they can recommend which state for where your LLC should reside.

Is this a flip, a buy/hold, or intended to be your residence?

Should we cash out refinance out primary residence to pull more cash out or should we just use own cash reserve+ HELOC for next down payment and any extra fees?

My question is the following, if I buy an investment property (while continuing to rent where I live), does that prevent me from qualifying for an FHA loan later on when looking to own my primary residence?

Even when house hunting for my residence a house would be gone within days of being listed. 

I'm talking about for my personal residence by the way, just in case I didn't make that clear.

Phoenix's Maricopa county grew the fastest last year with over 78,000 new residents.   

My friend has one on her primary residence and has used it 3 times since purchasing without much hassle.

Take a HELOC and house hack a 2, 3, or 4 unit with only 5% down as your primary residence.