Dreamer

I may or may not be getting a new Challenger R/T 6-spd before the end of the year, but being the big tech geek I am, there's a few things I'd like to know about the electronics.

First off, are there any cool features or gimmicks that would convince me to keep the stock navigation over a nice Kenwood unit? For example, the navigation in my mom's Toyota tells her when to change the oil, belts, rotate the tires, etc. Anything like that?

Does it have RDS (the thing that tells you what song is playing on FM radio)? SiriusXM?

Secondly, any cool features I should know about? Is there a current MPG gauge anywhere? Compass and thermometer?

Lastly, if I were to remove the stock stereo, would I lose any functionality in the car? For example, some Chevys had hidden settings that let you adjust things like when to automatically lock the doors and whatnot. If you removed the stock stereo, you lost access to those settings.

Thanks for the help guys.