I worked for MS a few years ago. I had a rather non-standard interview in that I was a contractor for over a year before becoming an FTE, so they already knew me well.
My interview consisted of me going in to my managers office and him scaring the piss out of me for a few minutes until he finally busted out laughing and said, "I was just messing with you, man. Fvck you, you're hired."
My interview to be a contractor wasn't too different than anything I'd had at any other job, although I would imagine each group there does things a little differently.
As for a rental car, it depends on what you want to do after the interview and where you're staying.