You're still shopping after 11 months?!
OK, you don't indicate your area so it's hard to answer specific market questions, but the colors you want may be hard to find as leftovers.
The Charger is a different model that sells in larger volumes and gets more goodies and, apparently, better incentives at times (not always). If you want a better equipped car, get a Charger or a 300: the Challenger is the sporty coupe of the bunch.
Yes, you can order without stripes or spoiler, and if you are dead set on colors outside of black, silver, white, or granite, you may have to.
That 20" rim deal... Again, if you order you can get the 18" ones without a problem; they're not bundled with the sunroof. Now if you buy from a lot, you'll have to get what's on the car. If you insisted, however, and the dealer was interested in your business, I'm pretty sure that you could convince him to swap the rims for some from on another car on the lot. Most people want the bigger rims, not the other way around, so it shouldn't be too hard.
The 2013 brochures... Dodge's marketing and advertising gets ragged on all the time here. You're better off monitoring this website for current intel (and no offense, but I don't think you've done that enough in a year).
Hope that helped some.