congrats on the first duplex. easiest will be house hack your next property. you can go higher in units up to 4 but just need to occupy the property. lets connect if you need guidance, i house hacked a few times

If you do acquire more properties, would you buy more S8 units and would they be in Dallas?

I believe United FCU is best. 20% down, usually a 10yr term (they offer a longer term though), and an interest rate that's pretty close to the current average for conventional loans. 

A water heater replacement is $1500, AC Unit $8,00011.

If you're planning on living in the unit during the winter and renting it out over the summer, you could have the best of both worlds.

I am learning "lingo", for me it is like a foreign language.  

And the problem is the other units?

List each building or rentable unit.  

As others have alluded to, buying larger units or a house near the beach is a better play. 

They provide fake checklists saying units are repaired according to agreed-upon inspection reports only to walk in to a home that is more damaged than it was during escrow.