Its very easy and not dangerous. I've previously used one click root methods which avoids any risk of a mistake. This time I did it manually (which took about 30 seconds longer) because I wanted to see how easy that was.
Nowadays there is really almost 0 risk. You almost never hear about anyone really bricking a device by rooting or adding a stable ROM or kernel.
That said, I'm rooted but running stock and my battery life is pretty decent. I typically go from 7am to 11pm, about 2-3 hours of screen on time, and rarely do I get below 20% before I am back on the charger for the night.
Keys to battery life:
1. Turn screen brightness WAY down. I keep it at 10% personally.
2. WIFI - use it. 4G houses battery power. If you have WIFI its a no brainer.
3. Turn off unnecessary syncing (I only sync Contacts, gmail, email, calendar, browser. Google+ is a known battery killer. If you don't need to sync it, turn it off (facebook, twitter, etc)
4. If you are in a borderline 4G area and don't need the speed, turn off 4G. A lot of people report that the 3g/4g hand off is a battery hog. If you are borderline, you'll be doing a lot of switching.