Ok you need odin and clockworkmod. You do not have to "root" the phone but the easiest way i found is just to get into clockwork recocery and make a nandroid backup. You can find this all online.
Theres also mobile odin that doesnt require computer but i have never used it. Also i think there might be some other apps like lookout that can make a backup. I think that your regular android recovery can backup too. Just turn off the phone and hold the volume up power and home keys.
Nah mate it doesnt, i used it to flash 4.1.2 without root coz i hate Kies lol (just remember use download mode, vol button down.
I bought mobile odin... i really need to find a tutorial lol i hate pcs :banghead:
Unbranded international rooted s3 with Official 4.1.2 JB. Paisley, Scotland, Western Europe :beer: