As I mentioned in my previous post...look at the Dupont Hot Hues....you could pick an off the self color that you like...as far as how much you need, I would suggest a gallon of each, base and mid coat. One gallon of uncatalyed clear should be enough as well (depending on how many coats of clear you plan on putting on the car...1 gallon should be enough for 2 coats of clear. Primer I would still recommend SPI epoxy if your going down to bare metal. You mentioned you may not be taking the car down to bare metal...if your not, you could use any 2K High build primer. If you chose to go the SPI route for your primer needs, you may want to also get their clear...I haven't sprayed it yet but have heard good things about it and will be trying it shortly...the product is also priced right.
I hope this answers your questions...as I said, a "tri-coat complete is a very ambitious project for any painter that may lack experience...not that it's that difficult, it's just that there are rules that need to be followed in order to get the end results that your looking for.
Below are several URL's of a tri-coat custom I did a while back. It was shot in PPG Vibrance with transparent orange over a blue metallic base...it has ghost flames on the hood, down the sides (3/4 of the way through the doors) and on the tonneau cover.
002 | Flickr - Photo Sharing!
087 | Flickr - Photo Sharing!
If you have any other questions, feel free to ask and I hope this helps.