05Sleeper- Congrats on the S4 :xyxthumbs I spent an afternoon with a 6-sp one and was sorely tempted (that's saying something for an A8/S8 nut like me

).
For fixing the existing marring, it'll just depend on how bad it really is. No way to tell until you start working on it. While *I* would probably reach for the rotary, sometimes you can do it with a PC/Cyclo *but* I've always needed 4" pads when working by PC.
Note that if your rotary technique isn't pretty good, you could quite possibly make things worse. I'd suggest you pick a single panel and try to correct it with the PC. Get an incandescent light for the final inspection and work in a shop where you can turn out all the other lights when you do that final inspecting. While doing most of the polishing I'd work under halogens- they'll show *most* of the defects, just not as many as the incandescents will.
Two examples of Audi clears and the PC:
Last year somebody brushed against the S8 at a resort...left a pair of long scratches down the passenger side. Just for grins I tried fixing it with the PC...worked fine but took a while. I used a 4" orange pad w/3M 05933 (many passes) then 4" white w/3M 05937, then 4" white w/1Z Pro MP.
Wife's A8- marring on trunk lid... 4" orange w/H-T EC (worked well), 4" white w/OCP, then white w/1Z WPS.
In those cases I didn't switch to the 1Z stuff (which can do some concealing if used on an imperfect finish) until I was satisfied with how things looked- I wanted it fixed, not hidden.
I've also used the PC to correct spots I somehow missed

when working with the rotary. Those spots don't show, they're just as good as the by-rotary rest of the panel.
So yeah, you *can* correct Audis with hard clear using the PC/4" orange pads. You *might* be able to do it with the Menzerna IP, but maybe not. FWIW I could never get any correction on that paint with the FP, so I'd get things basically perfect before switching over to it for the final work.
Honestly, I might go the route of getting it *close* to perfect and using a final polish with some concealing ability, then topping with something like 476S. While I like keeping my good Audi as close to perfect as I can, it's a chore (and that's even though I've got my wash down pat). To get yours literally perfect, and keep it that way, might be unreasonable.
I'd worry more about the LSP providing protection (and maybe a little concealing ability) than I would about the minute "benefits" that one LSP might have over another. I honestly think it'd look fine with Collinite on it but then I use UPP on the S8 so I dunno...
As mentioned, I sure wouldn't QD it. Well, maybe to remove a bird-bomb but no way would I want to try cleaning/dusting the car with a QD; I know I'd mar it. I'd just use it after the wash to provide some lubrication when drying.
Washing: I'd use a foamgun. Note that it took me many tries to get my foamgun technique figured out. There are some threads somewhere where I go into it, and I have a thread in the Hall of Fame forum with some off-the-deep-end wash techniques. Not easy, but they do work.
And for some reason I always found it very hard to wash without marring. I've been doing this stuff for a long, long time and it's only recently that I got the the point where I'm utterly confident that I won't induce marring when I wash. The theory is simple: don't abrade the finish by pressing something harder than paint against the panel and then moving it; the practice is *not* so simple...just how do you get that abrasive [stuff] off of there without moving it across the panels under pressure :nixweiss I use a foamgun,
David Fermani uses a pressure washer.