Everything should be in writing...faucet swaps, toilet paper holders, hand towel rings, etc. 

Establish a minimum criteria and stick to it, and if something turns up that rings all bells go for it

The home currently has a tenant and they want to stay he’s warned then of the possible sale and that within a few months I can increase rent to $800-$850.Taxes are $1604 a year and insurance rings in at $650 annually.

Compared that with San Antonio (like areas around 1604 ring), where you can get much better houses (newer, cheaper), but with low rents too, because there are so many. 

Go out there and start sending mail or writing letters to distressed homes that you find and start getting your phone to ring.

One tenant was making onion rings and a grease fire started.

Our primary residence has a considerable about of equity (Apparently that's true because I completed a HELOC pre-qual form online and immediately after I hit 'submit' my phone was ringing with loan offers and it hasn't stopped for the last 12 hours).

Step 1 is ALWAYS downloading your state and local LL/tenant laws, putting them in a three ring binder and reading and knowing them.Step 2 is taking Fair Housing Training, either on-line or in person, so you do not violate the law and get sued. 

@Jennifer Brown give McCaw Properties a ring. 

It will probably be a year anyway by the time you get engaged and then plan a wedding before you actually tie the knot and begin living together.Wait for him to propose and then plan a wedding for next fall or even if you get married earlier, it would only be a short time for him to have long commute.I'd say worry about where to live and commute times once engaged.