You can go to OCS after college or UPT in the AF with a guaranteed flight slot(Read: Don't sign on the dotted line until you see the slot guaranteed) My experience with aviation guarantees is very limited and dated to be honest. I know the Marine's for a time were giving out guarantees but not sure where that sits now. You're best bet for that information is to talk individually to Officer recruiters. Realize the information they are giving you now most likely won't be the same in 5 years when you're done with college.
As for the flight time reduction, it's like anything else, its cyclical, hard to say where it will be when you're done with flight school in roughly 6 years(4 for college and 2 for flight school). I do know this, there is a large move afoot both in the Navy and Air Force to replace flight hours with simulator time to cut costs. FWIW.