I agree that you should probably put this into Aspiring JETs and not Current JETs, but:
As far as recontracting goes, I'm not sure yet, but I believe that there's paperwork you will need to fill out and that every CO does it slightly differently. Usually it's done between December and February is what we were told at orientation this year.
As for the salery, I'm finding it's more than enough to pay towards student loans, live rather comfortably (if not lavishly, but then again, I never spent money before now), and still have a lot of extra money to save. I'm fairly rural though, so I don't go out a lot, and my BOE covers my rent, which is not the case most of the time. But even if you are in a city or more expensive placement, you will most likely be able to save money as well as pay your student loans... even if it means living on a bit of a budget for a while.