Question regarding re-entry permit. Please help?

[cztg]

I have first arrived here in the US last Oct 9, 2014 under an F-22 IV but I have to leave again on the 24th because school has already started in my country (I plan on finishing my studies there). I have filed for a re-entry permit (expedited) but as of the moment, the only thing I've received is the USCIS acceptance confirmation in the email and no notice regarding my biometrics sched. They have also deducted the $445 fee already. I've read that the USCIS can automatically reschedule people who missed the appointment and that they can do that like 3-4 times in 120 days? So, if I still am unable to return for the schedule within that 120-day time frame because of time and financial constraints, will the REP application that I've submitted become nullified?

Also, my semester finishes in 5-6 months so that's when I plan to return to the US again and stay for a little over a month. Can I apply for another REP again by then? So then I have an excuse to stay for over a year since I still have to finish 3 years on my degree.