Ok, to answer a few questions:
First off, definately ask the painter how long to wait to wax, each one is different. On repaints the paint needs to cure since it is not "baked" like factory paint is (straight from the factory the paint is cured and you are ok).
S100 is really the same thing as P21S, S100 has been found to be identical, just cheaper
You can find it at Harley dealers for $15 a jar. You shouldn't need a polish on a fresh paint job, but after the cure time, it wouldn't hurt, and the S100 SEPC (shine enhancing paint cleanser, also at the harley places fro $9) and S100 combo are awesome. There are some other great and easy to use combos I can suggest, but SEPC and S100 are available locally (pending you have a harley dealer around), and not too bad price wise. I can give other recommendations if you like. Also, what I recommend also depends on colors of cars as some seem to look better on certain colors than others.
How often to polish/wax depends. Every wax is different on the longevity. Carnubas are wonderful looking, but don't have the longevity of polymers/sealants. The down side to P/S is they don't have the reflectiveness, deepness, and wetness that carnubas have. Some people use a P/S and then a carnuba topper (ie topping it with carnuba, some combos work, others don't...loooks wise and chemically) S100 will bead for a good 2-3 months.
As for the QEW comment, QEW is a wash, not a wax