Brake Pads and brake fluid

I took the car to the track this weekend and time to change the brakes and fluid.  Where is a good place to buy pads and which pads should I buy.  Also, is this a bad do it yourself job?  I actually wanted to do the work myself but if it is overboard then I will take it in.
 
Also wanted to change the brake fluid.  How do I go about that?
 
thanks,
 
tim

by the way, car is an 03 996TT.
 
thanks