As for the questions – they are trying to get insight into what you wrote and how you view the position. They probably have a list of questions ready for you. As with any interview, be sure your answers are not “canned” – that they relate to the job they are advertising for, not just a general faculty job. So, your research into their department, program, etc is very important. Why do you want to work for them, not just in academia.
I find that there are basically two types of applicants – those come across that they are applying because they need any job, and those that want our job – very different ways of interviewing. The latter, obviously, is a much better way to go. Statements that start off with “In looking at your program, I…..” are very revealing. Educated responses are well-recieved.