Forgot to answer your question regarding Mods. All I can say is be very careful what you do, and if possible stay with Mopar parts and have the dealer install them. The reason is that I was told that they then become covered under your current warranty. You should have no issues if you do that. If on the over hand you want to go outside of Mother Mopar...check with your dealer first. Better safe than sorry, as it would be very hard to win a case against the manufactuer if they can show you mod'ed the car in any way. Since your warranty clearly states that mods will void the warranty.
As for 87 oct fuel useage, you should have no problems as I have used it from time to time when nothing better was available. However, if you use lower grade fuel just take it easy and don't lead foot it as your engine could knock......