Yeah, you can wash it. You can even polish it (chances are the paint shop already did, they may have even wetsanded it), but note that the paint will be a little softer than normal while it's curing. After my S8 was repaired, the painter and I both wetsanded, compounded, and polished areas of its fresh paint shortly after he sprayed it- no problems, and it was easier to work before it was fully hardened. Watch that you don't use a polish that contains wax, though. During this time, the paint is "out-gassing", so you don't want to seal it up with wax or a sealant, but there are numerous products that you *can* use safely.
For protection, there are fresh-paint-safe polymers that give a little more protection than the 3M IHG. Meg's #80 is a good example- some mild abrasives, fresh-paint-safe polymers. Other Meg's "pure polishes" work OK too- #3, #5, #7, #81.
Don't use a carnauba-based QD, but yeah, Meg's #34 is perfectly safe, paint shops use it on fresh paint all the time, but it won't really leave anything beneficial. Best to use one of the glazes so you have *some* sacrificial layer over the sorta-fragile new paint.
FWIW, I use either the #80 or IHG on fresh paint. Never had a problem.