Interviews depend on the school. Probably about half do interviews. I have done a few interviews so far, though not for Brown.
Questions are usually how you came to be interested in religious studies, why religious studies for your area of interest, what are your main research questions, why this particular school, what are some formative classes you've taken, or formative books you've read. It's probably normal to expect 1 or 2 questions you didn't prepare for.
Be sure to reread your statement of purpose and be ready to answer any clarification or follow-up questions. Hope this helps, and good luck!