My goal is to slowly build an inventory of rental properties for additional income when we are out of the military.  

Jennifer, I know Myrtle Beach has a strong military presence, might be an option for buy and holds and flips.I would make sure the house is able to qualify for VA financing when its completed. 

I have heard the military bases also have students etc that come to town for certain trainings and need a place to stay.

Likely no relation but I do have some family members in the military. 

I’m new to REI and very interested in starting out as soon as I save up more money or when I get out of the military.

We currently have one rental and have been living on the military base but we finally were able to get ourselves into a second house.

Or police, firefighter, military, discount?

I am a veteran great move to join the military i applaud you. 

Most importantly, does any of these submarkets have any economic anchors like state government, major universities, major health care centers, or manufacturers that are independent of the economy like military suppliers that employs most of the residents of that submarket?

If you are military you maybe looking to USAA for your investment property the same as you would for personal property (that's what I did).