Ok, I'll chime in. I'm an EMT-B and have worked as an ER tech for the past 2 years. No you do not have to be an EMT to work there, but I think it helps. You do alot of the same stuff you learn in EMT school, like EKGs, CPR, basic vital signs, wound dressing, suture removal, splints, lots of cleanup, patient transport (to x-ray, the floor), and also more such as phlebotomy, catheters, assisting with spinal taps, suturing, pelvic exams, etc. I also triage patients when the nurses are tied up and I sometimes take reports from the paramedics. It really is an enjoyable experience and when I have free time I can still ride with the ambulances. I recommend working in the ER, if only part-time, just to gain the confidence and experience in how the dept. is run which can be especially helpful if you plan on an EM residency. Granted the hours are killers, at least mine are since I switch back and forth between days, nights, and midshifts all throughout the week (12 hour shifts), but like my friends tell me, I'll be ready for residency. lol
I hope that helped some, and good luck in whatever you do.