Also, ask these questions from a few graduate students. You will get different answers from different people. Be ware of the ones that are about to finish, they can be the most cynical. We all are pissed off at that point.
I would add: "Who in this department would you not recommend working with?" You will get an honest answer and probably some more insight into the politics/atmosphere of the department.
Good luck with your interviews! Once you are there, you will find that the feelings you get from people will speak volumes without them answering any of the mentioned questions.
+1
