N/A Question for you 350z gurus

I'm looking into purchasing a new vehicle, and the 350z is the only car that appeals to me. I've got a few questions, as I've never researched this car before, and i honestly can't find the answers to all my questions by searching.

What kind of power does it put to the wheels, 100% stock. How much does it weigh?

What kind of differential does the car have?

What can I expect to pay for an 03, 04, or 05?

Any major problems with the older models that I should be aware of. Also, any differences in the years. I tried asking a salesman the differences, but he didn't answer me with a real answer.

Also... What kind of power can I expect to net with an intake, headers, exhaust, test pipe(s?), and a set of more aggressive cams with keeping the stock redline?

What piggybacks are out for the car?

Thanks for any help you guys offer.