If you dont have any experience it might be a little challenge but if you go to a custom shop or even the dealer they can do it with no problem. You can do a search on here about that, I know theres tons of threads on installs and what you'll need.
Yes, you can buy the Nav and install it, if it didn't come with it from factory. You can buy one from the dealership, the recommended route, or you can try eBay, but you run the risk of buying a bad or stolen unit.
It's a pretty easy install. Check out Moparsupercenter.com. The wiring is plug and play. You can install the nav antenna right above the air vents. You can buy a new Orange bezel with the navigation cutout from the dealer or from moparsupercenter.com(cheaper this way)
i did it with mine and its really easy. you just have to go to your dealer and have them order a new cover. it fits great and it was def. worth it. Now im just waiting for the new my gigs to work and then im getting that.