BlueBoxer1- This must be sorta confusing, you're getting conflicting advice. Heh heh, and I'll probably add to that confusion

And I'll admit that I take new-car delivery to extremes because I want a truly undamaged new car. Long-winded $0.02 follows:
IIRC, four of the last six times I let a dealer remove the plastic (one Audi, two Subarus, one Mazda), they messed up the paint in the process- at least one deep scratch, too deep to be removed and enough general marring that I had to do a full polish. No, I didn't refuse delivery in those cases, but I sure thought about it and pointed out the damage which they initially tried to shrug off. If you let them take off the plastic, let alone wash it, you can almost bet your life that they'll mar the paint. How badly? :nixweiss But they *will* mess it up.
FWIW my Porsche/Audi dealer (Stoddard Imports, a *good* dealership) insists that the next time I buy a new vehicle from them I take it "in the wrapper". They readily admit that their guys can't unwrap/clean it without messing it up according to my standards. And yeah, if I found damage they'd take me at my word and take the car back. But dealers who'll treat you that well are pretty rare.
I've removed the plastic on quite a few new cars,it's my general MO for taking delivery (yeah, you can drive them home with it on and no it doesn't flap around- if it's that loose just peel it off before you go). In *one* case (a '95 Cadillac) there was paint damage under the plastic and it was a horrible experience trying to get satisfaction (terrible dealership), so yeah, that bit that
STG mentioned about wanting to know about problems has its points. But honestly, on a Subie, I'd take my chances with that risk and yeah I'd drive it home with the plastic still on it.
Other option, if you don't mind getting some weird looks, is to do what Bill D did with his Mom's Benz- he unwrapped and washed it at the dealership with his stuff (see below).
The best thing for removing the wrapper's residue is New Car Prep from
Automotive International - Valugard Product Line. It's a vehicle-safe (won't mess up anything) solvent. Sometimes the residue and be very tenacious and having the right stuff can make a tough easy. I'd rather use a solvent than clay aggressively.
FWIW I also always use AutoInt's decontamination system on my new vehicles, but that's a bit of a job and I understand that many people won't want to bother with it. I clay while the acidic step is dwelling but then I'm a bit paranoid about rust blooms from ferrous contamination.
I'd plan on using the paint cleaner if you don't decontaminate. Be careful with the clay so you don't mar the paint.
Otherwise your proposed regimen (as in your last post) looks good. You just don't know what it'll need until you see it.
I'd have some kind of understanding in place with the dealer. If they prep it (at all) and mess it up, what's the fallout gonna be? If you prep it and find damage, what's gonna happen then? Give it thought and *get it in writing* no matter how much of a hassle it appears to be at the time. Yeah, I've refused delivery before and I'm glad I did.
LSPs: I like to get numerous layers of LSP on a vehicle, but you don't need to do it all at once. You can add another after each wash for a while.
Garage floors...painting a dirty floor is problematic and involves acid-etching and lots of prep work. We've discussed it in depth in a few threads, probably worth the dreaded search. My previous shop had an unsealed/unpainted concrete floor (sections of which dated back to the '30s and those areas were sure dirty) but it wan't a problem. But some concrete floors dust/etc. more than others. Maybe you can get by with it as it is, maybe you can't.