just bought 350z.. engine clatter and brake question

i just got a 35th the other day and i noticed when i shut off the motor there is a bit of clatter and if i have the clutch in all the way to the floor and give the throttle a blip there is some clatter i hear.. is this stuff normal for these cars?

also the car dosnt seem to stop good even with the brembo brakes it has... im thinking the pads are glazed from when the car was driven in from another dealer or test driven by someone before me.

That doesnt sound good, I would take it in. Sounds like something with the Trans Gear Box or something near the clutch and flywheel. Have you been dropping the clutch? Grinded any gears?