Congrats to everyone accepted, and to those still waiting, there's still hope. Some people in my class didn't get in until June, so there will be more acceptances to come.
1) Some people in the current class do not have a car, but their lives are a lot more difficult than those that do have a car. I would strongly recommend getting a car. While the trains and public transportation are great getting to and from the city, they're not as useful for getting around long island.
2) About half of our class lives on campus and half lives off. I live off campus in a house in Westbury with 5 other med students and we love it. The rent is cheaper than the dorms, and you don't have to deal with a 24 hour security person to sign in your guests. We found our house on Craigslist, and it has worked out pretty well. I personally took a year off before med school started, and hadn't lived in a dorm since sophomore year of undergrad, so I didn't want to go back to that style of living. Some people really like the dorms though, so make the decision that's right for you. The proximity to school can't be beat (for the dorms).
3) I think if you live on campus, you are required to have some kind of meal plan. I eat on campus about 3-4 times per week, but I don't have a meal plan. There are plenty of restaurants around so you won't go hungry. I don't cook all that much, but my housemates do, so I mooch meals off of them whenever I can.
Our class is really excited to have you get here. Good luck with everything! Feel free to PM me if you have any questions.