You're sure you've got 17" wheels right? The current Saharas come with 18" wheels. I think we talked about this before though and you determined that you did, in fact, have 17" wheels.
That said . . . .
1) Yes. You can pay some money to get them powdercoated, but I know there are several folks who had very good luck with spray-on bedliner they do at home. Just buy a few rattle cans and do it in an afternoon. You can fix any chips or trail rash with another squirt. Take a look at this
2) Yes. Don't know the price, depends on the area. Look on Craigslist and see what's being sold in your area now.
3) Depends on what you can sell them for and what you're replacing them with, but I have a hard time thinking you could do better cost-wise than a few rattle cans of bedliner.