I just rooted my phone for the first time (any phone, as this is my first android phone) a little over a week ago. Honestly, every phone I get I will probably root it right out of the gate. Been a great experience, but it helped I read a ton before jumping in. I probably won't be an early adopter of anything simply because I rely on my phone too much and if I'm without it for an extended period of time, that could lead to bad things.
Time Without Signal = Settings -> About Phone -> Battery Use -> Cell Standby (click on it). That will give you TWOS as a percentage.
To answer your second question, yes, there is an app out there which will tell you what specifically is using your battery. I believe it's called "Spare Parts" but I've never used it, just read about it. Great reviews to get a good look at what's really going on.
As for the TWOS "bug", here's the gist: Most people seem to think it's draining your battery as it seemingly is ALWAYS searching for a GSM signal (see previous post as to why). However, many people have noted that the TWOS is usually exactly half of the uptime (or something like that, maybe it's double, I cannot remember right now) which really means it's not looking for a signal at all as it's had a perfectly fine CDMA signal the entire time it's been up. 50% + 50% = 100%. There's a good explanation in one of the posts in about a 350+ PAGE thread on XDA but I don't want to go searching for it right now.
So in the real world, it's not looking for a GSM signal, at least, not as far as the battery is concerned.
I would recommend putting a ROM on there for good battery life as well. I'm using the SyndicateROM Frozen (Standard) right now, and my battery is lasting MUCH longer than before. It has a scaleable kernal attached to it, so that probably makes the biggest difference. You can check out the thread for that ROM in the "All Things Root" section for more details. Highly recommended.