First of all, BREATHE!!!
Secondly, congrats on the interview!!! I'm very happy for you to get an interview for the nursing floor that you want.
When you have an interview, make sure you dress well, dont wear scrubs
As for the questions you should ask during an interview, here are a few:
1. make sure to ask how long orientation is
2. will you have the same preceptor or a different one daily
3. what is the shift you will be orienting on
4 after orientation what shift will they place you on
5. If you feel you need another week of orientation will they give it to you
6. What is the nurse to patient ratio
They will probably ask you about yourself, why you want to do L&D, they may ask your strengths and weaknesses (be prepared to answer that one), and they may ask about your clinical and what you think nursing is about.
Good luck with the interview!!