I've been using a ROM on my ATT Galaxy S3 that has been acting weird; maps force closing, black screens constantly, apps freezing for extended periods of time, and I want to start fresh. I'm going on a road trip for the holidays and would really like to use maps as they were intended.

I wiped all my personal data but there are still some pictures showing up in gallery and some app folders that didn't get deleted. My understanding is that this is all on the internal SD card. I know I shouldn't have to worry about it too much, it'll just make me feel better. Is the ROM itself (AOKP 4.1.2) on the internal SD card also? If I were to go into CWM and format the internal sd would I lose everything and would the phone be unable to boot or would I be able to simply re-flash the ROM? if i were to put the new ROM on an external SD card would i be able to go back into CWM and flash it from there?

If I'm missing something feel free to correct me or point me in the right direction (a guide would be ideal). I've searched on various sights and can't find exactly what I'm looking for, everything seems a little vague.

Thanks a bunch and Happy Holidays.