I have a PC7424XP with LC 5" and 3.5" backing plates. With that said, here are my questions:
1. How many pads? I'm thinking 3x 5.25" cutting, 3x 5.25" polishing and 1 each of the 4" pads.
Typically you will need double the cutting pads compared to polishing due to the amount of material cutting pads remove. Claying and decon helps, but I'd still get more cutting pads. Also, MF pads need to be switched after a panel or two to prevent thermal breakdown. You can use them again after a couple of sections. One each of the smaller pads should be fine unless you have a lot of cut in work and then I'd get two cutting pads.
2a. I don't have the new spray G-P-S. Will liquid PoliSeal be fine?
Yes, but most people use too much and it clogs pads prematurely. So after you prime the pad, you will only need to add a little. Placement of the product on the da should be around the outer edge, while if using the rotary you'd put it closer to the center.
2b. I'm planning on using Hyper Spray Compound with the cutting pads followed by Hyper Spray Polish with the polishing pads. Do the polishing pads finish down LSP ready or will I need to apply PoliSeal first as a finish polish?
That depends on the paint. Always do a test spot to nail down your process on each car.
3. What's the proper method for cleaning MF pads? Is
Detailer's Pro Series Polishing Pad Rejuvenator safe to use?
You only need to use laundry detergent. The product you mention is made for foam pads. If you need stronger cleaning, presoak in warm water before washing in the washer.
Thanks for all your help everyone.