As far as the header goes, yes, only one. As for the exhaust, I would say go magnaflow. Two of the guys in my car club work for pacesetter and neither one of them would put one of their exhausts on their cars.
No you wouldnt need the CAI on a turbo set up.
Remember one thing when it comes to modding out your car and thats the same thing I was told when I first got into and its something I pass along as well as Im sure many other people do as well....."Speed costs...how fast do you want to go?" and the big mainstay with most things "You get what you pay for." If it looks like its to good to be true chances are...it sucks ass.
As far as websites and such goes I think maybe tonight Im going to post my little black j-body book. I think I have a pretty big selection of different places to pick up j-body items.