What questions do I ask about Rental Properties

Besides the obvious questions like (rent rates, current leases etc.) what other questions should I be asking about multi-famil rental properties (2-4 units).

I am getting ready to make the leap into a college neighborhood where rent rates are very strong, upkeep and maintainance are on the high end, but with little to no vacancy.

Thanks for the input. I am just waiting for the right property to get the numbers to work the way I want them to.