Right, well since not all of your questions are generic android ones, I've moved your post here to the Ally section. (I didn't go for the rooting section though - I don't know about the 50% bug so I don't know if it's root related). But I'll answer what I can.
Ok, so a ROM, in this case, is referring to firmware for your phone. So at the moment you, presumably, have stock firmware on your phone. But you can switch to a custom firmware (a.k.a. a custom ROM). These are usually improved versions of stock firmwares, or offer features not available to your phone through official channels (e.g. newer versions of android - so that's how you get your hands on 2.2).
I'm not sure what you mean by Titanium nearly bricking your phone. Bricking means to literally kill the handset, so it can't be booted or recovered at all (and so all you have is an expensive brick
). Titanium should be able to remove any app in a few seconds without much hassle - what happens when you try it?
If you're having reception issues, you might want to flash a new radio. But, beware that flashing a radio can brick your phone (Firmwares can't, even if the flash goes wrong). The important thing to remember whilst doing this is:
Never, no matter what happens, pull the battery. So make sure you have a full charge first. I'll have to let an Ally user point out the way to a new radio