You’re able to learn the basics of a real estate investment with lower risk and build equity at the same time.Because you're in the military, you'll be able to enter a property with 0% down which means you can leverage your money way more effectively. 

We took the reverse action and started lowering asking rents until they moved.I suspect the reason that one property of yours turned quickly is because your asking rent was very favorable vs. local competition. 

Local banks typically offer lower interest rates but might require a solid track record and detailed financials.

I would just take into account that a lower down payment will mean a higher monthly payment so be sure to run the numbers conservatively in order to ensure your STR revenue is able to carry your monthly payment with this higher mortgage cost. 

BoA is fine for this sort of setup.. but consider a local credit union in San Diego for lower fees and simpler sub-accounts from what I’ve heard.

This implies residential units can be built at lower costs and provide better return. 11) adding an ADU to SFH can make the SFH fall under rent control.

I would like to have lower monthly payments should I make a big lump sum payment towards my principals and ask my mortgage company to adjust it or refinance it or which one is the best ? 

Seems like it's in a lower end area so if it is filled you will have tenant issues and turnover cost.

If I have lump-sum free cash, should I just apply it to my mortgage to recast so that my monthly goes lower?

When you researched markets like Austin las Vegas Miami, those markets have higher land cost and are more cyclical in nature tend to have larger price swings compared to regions with lower land costs.