Glad your LTE is solid.
It would appear that out-of-the-box you'd run 4.0.4 Ice Cream Sandwich (Galaxy Nexus was the ICS poster child after all), but you have update options of 4.1.1 (initial Jelly Bean) or 4.2.2 (latest [so far] Jelly Bean).
Keep your eye on that UT progress... I've been blogging about it on the Mobile Nations Forum (Beta) and will update again soon.
http://forums.mobilenations.com/ubuntu/464-i-wanted-try-ubuntu-touch.html Canonical has not ruled out creating CDMA drivers so Toro could partake of the OS, but they've not announced any progress either. CDMA is notoriously closed tech.
Rooting gives you more control over your phone and its performance if you follow it up with mods. Be sure to unlock your bootloader first thing, if you are at all interested because it will wipe whatever you have on the phone. Better to unlock early, rather than after you have a lot of set up done. WugFresh's Toolkit makes it easy to unlock and root. It also has restore options. It's a very nice toolkit, IMHO, that makes things easy for beginners...
Speaking of beginners, I'm one too. I used Android in the long ago of Cupcake and just was a phone user. I never flashed or modded. Now I'm on an N4 coming from webOS. Looks like you are coming from iOS? Did you jailbreak, etc? Comfortable modding a phone? It's different experience, but helpful, I'm sure?