Titanium Backup is a must, it will backup your apps and their data. Be careful with restores, I typically let the Market redownload just about everything and only restore data to some key apps (saved game progress in some cases, Google Authenticator, ConnectBot [I've got a few complex setups], etc.). The more you install fresh the more stable your system will be.
Personally, I'd recommend either Liberty or CM7 as a starter ROM. Liberty because it's easy, CM7 because it's the current hot ROM so you'll get a lot of discussion on it.
Liberty is based on the Gingerbread Moto ROM but needs the donate version of the Liberty Toolbox installed to access it. It's very easy to install, full-featured, and lets you use the Moto apps as needed.
CM7 is probably the most popular ROM because it runs on a lot of phones. It's still pre-beta for the X, but works well. The downside is that it's not based on a Moto image so you don't get things like HDMI support, the Blur camera (which is excellent, BTW), or some other features. It's also a work in progress so expect bugs, poor battery life, and frequent update opportunities. To install it you'll need to drop down to Froyo to get the older kernel, but it is a Gingerbread ROM.
There's some discussion of other ROMs in this thread, all worth researching:
http://forums.androidcentral.com/mo...cks/92154-rom-stock-matter-you-poll-time.html