Hi Vader... PAC is a great source but, in all honesty, the recently discovered autodetailingsolutions.com has some EXCELLENT deals on PC (Meguiar's labeled) kits. The Meguiar's G-100 (PC) comes with a lifetime warranty unlike the Porter Cable...
As for the pads with ADS's kits, if I was buying it, I'd ask that they substitute the 'Cutting Pad' for another 'Polishing Pad' as the cutting pad isn't made to be used with the PC. Also, depending on the kit, I'd make sure you have at least two polishing pads and two finishing pads.
Make sure you have several hand (foam or terry) pads on hand. You can snare these at your local 'mart' store. I'd recommend the Meguiar's Even-Coat Applicator (a microfiber applicator) or the High-Tech Applicator Pad (foam). You'll need these for the areas you can't address with the PC because of trim, glass, or other obstructions.
Your question about the bonnets and pads is a bit confusing... Let me try to clarify.
Pads will be used to apply the products, bonnets for removing. Generally speaking, I'll use an old, worn polishing pad and place a DF Towel Bonnet or Ultimate Bonnet over the pad and remove my last step product sometimes. More often though, I'll remove by hand. Further, I'd recommend removing abrasive polishes or cleaners by hand as they have no purpose to dry completely on the paint.
Different pads for each individual products is a must in my opinion. Polishing pads will be utilized when you are cleaning or polishing the paint. When applying wax, a finishing pad should be used. You'll want a few of each like I mentioned earlier. These will last a while if you take proper care of them.
Does that help a little? Let us know if you have any other questions!