1. Killeen is actually the largest town between Austin and Dallas - larger than Waco, Temple, Round Rock, Georgetown, all of them. That said, yes, it is still very much a military town. Fort Hood is America's largest military post by population in the world. It is not going anywhere. The down sizing was announced already and added up to about 3500 Soldiers for Fort Hood, to be complete by 2017. The market has begun to diversify some with a large military retiree population and related hospital and healthcare services/jobs, as well as the new and expanding Texas A&M campus. Any area has risks, but a market downturn in our area won't be because of Fort Hood up and running.
2. I'm not entirely sure what you are asking. Harker Heights is a more expensive market. The median non-builder/foreclosure home sold in 2nd Quarter of 2016 was $187,000, versus $134,800 for the Fort Hood market as a whole. Only Salado has a pricier market (I don't include Belton/Temple and don't know those markets well). Days on market were 37, shorter than the 43 median for the entire Fort Hood area, so it is definitely a good market to be in. That said, you will still want to be particular about what kind of home you buy with an eye on resale/rental. 4/2/2s is what I would focus on.
http://www.hoodhomesblog.com/market/blog/fort-hood...
3. I have an article I recently wrote on the rental market update and what kind of vacancy landlords are seeing in between tenants. BLUF: about 40 days seems to be the median for those rentals listed on the MLS. It is also very seasonal - in June, rentals are getting filled a month out. In November, good luck.
http://www.hoodhomesblog.com/investing/blog/what-t...
Hopefully the moderators don't block this post - these are just articles I wrote with information and graphics/tables - I'm not selling a product. Linking to this info is easier than copy pasting it all.