I was told my brake pads, rotors and serpentine belt need replacing?

I have a few questions. I'm not very familiar with what was given to me today I need some urgent help. For the past about two weeks when going on the freeway my car shakes a bit when braking at high speeds other than that everything is normal and braking is normal in other cases. No noises or other problems. I went to get an oil change today and the guy gave me a full list of things I need. He said I need to change front and back brakes and front and back rotors. And also the serpentine belt. I guess it's hard to answer this question without actually looking at the car, but generally do I have to really replace all four rotors and pads? As well as that belt? I have added the note he gave me. He quoted me $580.00 for all four changes. Plus 60 with belt. I don't know anything about this stuff and don't want to waste money I certainly don't have to.