actually its usually the better jobs that promote faster because the military does not pay that much so people with the chance to get a high paying civilian jobs get out and leave room for lower ranking people to move up.
and every service will give you a specific school in writing (assuming you score high enought of the asvab) but, the as far as i know the marines are the only ones that will change your job
thats funny, we were just talking about it the other night at work, i thought the same thing but…no the airforce has more that was just a rumor.