HBblazer - I'm new to detailing the "correct" way and have learned a lot from Autopia , but my product choice is Meguiar's. Based on Meguiar's web site, which I have posted below, the Machine Glaze #3 is for use with a rotary buffer, but I don't see any reason that you can't use your PC. I don't think that the heat that you can build up with a rotary is a necessity to make the product work. You might try to post your question on the Meguiar's Forum for a more exact answer. I also think the finishing pad is the correct choice for either tool. I can't say the results will be different since I have never used #3, my personal choice is #7 with a PC.
Machine Glaze - The ultimate machine-applied shine. Meguiar's Machine Glaze lets you achieve a deep, rich gloss unmatched by any other polish, glaze, wax or sealant. Rich nutrients penetrate and revitalize all paint finishes, as well as fiberglass and plastic. Buffing residue wipes off easily to reveal the original brilliance and clarity of your finish. For use with a rotary buffer only Made For Professionals