Stateside there aren't, atleast none that I know of, however when I was first stationed at Seymour Johnson in the late 80's all I had to have to get something in a bar/club was to flash my military ID and I'd get served. Overseas bases usually follow what ever the local laws are concerning legal age.
Nope! They are either adults or they are not. By your post, you agree that those in the military should have that right, and I agree with that, PLUS every other right that should be extended to those old enough to vote, enlist, etc., not just those who sign up. That's by having the age of majority at 18. OR Raise it to 21, and not allow younger than 18 to vote, enlist, enter into contracts, marry, go to adult jail, etc. They either are mature enough at 18 or they are not.