Yes. The day a service member swears in and leaves home for basic training they are placed on active duty status and remain there regardless of their actual job until graduation. Upon graduation they...
With few special exceptions, no. You would have to complete your Air Force contract first. As for the exceptions, we'd be talking about something like attending and completing BUD/S as an Air Force...
Yes you can quit basic training at any time, and receive a complementary bus ticket (possible plane ticket) home in most countriesI know while I was in Basic I tried to quit and they made me go speak...