Congratulations on the interview Allie. I'm an RN working med/surg too, and wanting to move into public health. I have the BSN/PHN, but only med/surg experience the past 6 years. I interviewed with my county a few months ago, but sadly didn't get the job. It is very competative here, where I live. I was applying against PHN IIs, where I would have been a PHN I.
Well, I can't say what your interview will be like, but for my interview, I was met with a 3 person panel and case study questions.This was for a field position, however in maternal/child. They were tough questions, and nothing I could have prepared for (believe me I did try and prep for it). I think I did well, considering, and the manager urged me to apply again. So, in the meanwhile I am going to do some PH CEUS while I wait for another opening.
How wonderful to get an interview! Just use your common sense, and I'm sure you'll do great! Best of luck. Hope you come back and post with some good news.