I'd say no just because, being in the military, I know that a lot of guys in tend to rush relationships and you should enjoy your youth without worrying about relationships. I know a guy who's only 19, got himself in a relationship with a girl several years older who talked him into marriage within 3 months of knowing each other, and now he's about to be a dad in a few months. Be careful trying to jump into a relationship. Don't want it to control the few precious years of youth and freedom you have before the seriousness of responsibilities really hits you.
Yes, because you're not legal yet. Any guy who dates you could end up going to prison for "rape", even if it was consensual. You really want to ruin some guy's life? And you really want to date someone in the military when they are gone all the time and you never see them?
I don't think a lot of the quality guys out there on dating websites, will be interested in dating a teenager. And if they are, they are likely really creepy... like Jared from Subway.