1. If I become certified now, what am I able to do exactly? Will it be different when I turn 18? You will be able to do everything an 18 y/o EMT can do. The only difference is you will not be allowed to sign legal documents until you are 18, and there fore can not make up the minimum staffing for an ambulance in NJ ( 2 EMT's ). Most ambulance squads will let you run as a third and the other two emts will more than likely be willing to let you "take the lead" on calls so you are able to gain the experience you want.
2. All of my colleges are out of state, how would I go about becoming re-certified?
There are two options. After completing your EMT class within 12 months you can take the National Registry test without having to redo all of your practical skills ( your course director for EMT will have to vouch that you passed all of your practicals in class), and then you will just have to test for your NREMT-B card. ( National Registry Emergency Medical Technician - Basic , if you don't know the acronyms yet. ) Then you will be able to use that card to practice as an EMT in many states.
See
http://www.nremt.org/ for more information on that.
If you choose not to do that many states have a reciprocity process. You will have to contact the OEMS office in that state you wish to gain your certification in. By doing this process you are "challenging" the EMT course in that state against the one you have taken. Then the state reviews the materials your EMT class had completed and see if it meets their EMT course's minimum expectations and goals. Then you may have to take that state's written test or you may not. Then they will grant you your certification in that state.
3. I don't understand the distinction between volunteer and paid in terms of certification and work, can you clarify?
Volunteer : Does everything the paid guy does except gets paid.
Paid : Does everything the volunteer does, but gets paid.