1. First of all, the AF will accommodate you whenever possible. That said, everyone make sacrifices. You will certainly have to make some from time to time as well. That's just how this business works. As long as you're willing to "take one for the team" every once in a while, you shouldn't run into any problems.
3. The military is not much different than other slices of society. You'll find your crowd to run with, and distance yourself from others. When it comes to work, personal relationships are very important. You'll find some guys that are all about "getting girls," some that are not, and some that are in between. Some people are drinkers, some are not. Wherever they fall on the spectrum, you need to be able to work with all of them. They are your second family, and just like your blood relatives, you don't get to choose them. Drinking is not an issue. If you don't want to drink, you don't have to and no one will make you. Just don't let that be the excuse to avoid hanging out with your peers.
That's entirely up to you. People will develop that opinion only if you give them a reason to.