rrr,

I just got my GC while on F1...as far as I know, your F1 does not automatically gets cancelled...it will....but only after you get your GC, and you will have to go to DSO and give them a copy of your GC, and USCIS will later change your status to PR status.....But while your I-485 is pending, you can travel back and forth with AP without any issue (that is why they created AP) with immigration (but might have to talk to some of those airlines' moron, as Kristen have written) and your current status (F1) does not matter. You do not need to apply for F1 visa, but just to be safe, I would suggest you to see your DSO and have him sign your I-20 (you do not have to tell you International program, about your GC process)

...So, bottom line with AP you can travel in and out without immigration issue, your current status does not matter...But mind you that you have to have a Valid Passport. Also, your F1 will not change automatically until you are granted a GC. ...so good luck!