How do I interview with a "recruiter" or HR person?

I have an “informal” interview next week at a large biotechnology firm. It will be in two parts. One, with the department head (who would be my boss), and the other with their main recruiter/HR person. I feel comfortable answering questions about my eduction/work experience, but I have never had an HR interview. Does anyone have any pointers? Also, my specific concern is how to deal with compensation issues if the recruiter asks how much I expect to be paid.