Imtiaz,
I completed EMT-B back in '98 after graduating from college. Many of my friends were EMT/FF's and it seemed like a great way to get experience. I would agree with the above post about it being one of the best ways to gain experience in medicine as a pre-med. Volunteer experience is great, but in the end your responsibilities are limited. This is not to mention volunteer experience is usually observing and not actually doing. Working as an EMT-B, -I or -P will give you invaluable clinical experiences from which to draw from while you're trying to sludge through the first two years of basic science. It's one thing to read about a condition in a book and a whole 'nother thing to actually see it in front of you and be responsible for that PT until you make it to the ED.
Enough said about the benefits. The training for EMT-B is usually one semester (twice a week for about 3 hrs. / night). There is a class final and then a National Registry test (in most states). You are then certified for two years. Work is very easy to find if you live near a big city. Many private ambulance services are in constant need for good, knowledgeable EMT's. If you live in the country, you can usually get on at a fire department as a volunteer (FD's are also in constant need of EMT's). You're best bet is to simply call up a service or FD and ask if they need EMT's. Explain your situation and often times they'll sponsor you for the class (otherwise it's about $500). About hours, they are usually very flexible. Most times you let the service you're working for know when you want to work and they schedule accordingly. Beware, however, that if you sign up to work at night there is the possibility of spending the whole night awake running calls. Good luck, and if you have any questions send me a personal.
Dr. J?