There is a basic assumption you made here. Once your F1 status transfer is complete and you received the approval notice from USCIS. You can choose to go to either Canada or Mexico to get your F1 visa before you go back to China. But if you only want to travel in North Ameica, you don't need new F1 visa stamp to re-enter US. You do need your international student advisor to endorse your I20 and you can keep your I94 when you cross the boarder if your travel is within 30 days. But you ned to amke sure your name is on SEVIS. Probably not a good idea to travel before your school starts.