I am a dental student on NHSC scholarship. The interview was pretty laid back. If you are lucky you can interview in your hometown, otherwise it shouldn't be too awfully far away. There are 2 interviewers and they have a list of questions that they ask you. From what I remember none of them really were difficult. They ask why you want to be a dentist, where you will be going to school, to describe yourself and give a brief history. I think they also asked about leadership skills, strengths and weaknesses, why you want to be a part of the program. They will also stress to you that you have to be flexible in where you want to practice and other requirements of the scholarship. They give you a lot of time to ask questions and they give you a cd that talks about the program and some other information. I wish I could be more helpful but it seems like ages ago that I went to my interview even though it was only a year ago. Feel free to ask me more questions, it might jog my memory.
I really like the scholarship. My only problem with it is that I can't get things like burs covered because it is an individual expense and not part of the billed expenses of the school. Not really sure how they can tell me burs aren't required to practice dentistry but they do. My only other problem was that you don't get any money until November so I actually had to borrow a month's rent from my parents because I ran out. Just plan ahead and you should be set though. Other than that I love the fact that I don't have to worry about loans like the rest of my friends do.
I am not really sure what the selection criteria of NHSC is. I know that they want flexible people and people that will stay in the site even after their service commitment is up. I am an extremely average person so sometimes I don't know how I stood out to get the scholarship. I did live in a very small town for a while though and then a big city so I have experience in both types of envirnoments that I might be working in.