I don't have the reg in front of me, but I believe that is true. I was PV'd into Major under this example, so to me, that makes it possible. That has been over 4 yrs ago, so I am not sure if anything has changed.
IRT to the AGR promotions, it is regulated by the "Control Grade" issue as previously mentioned. A good thing to remember is that you are not automatically added to the "control grade list", you have to make sure that HRO puts you on it. I do not believe they will do it unless you (or your supervisor/commander) ask them to do it and it has to be requested via e-mail or memo. I am lucky enough to be in an O-5 position and on the control grade list-I believe I am #1 on the list for O-5 promotion when I become eligible later this year. Doesn't mean I will automatically get promoted, but will be promotion-eligible and that all of the wickets that I can control have been accomplished.