There's an app on the phone simply called "Talk", you'll see it in the app drawer. It signs in automatically when you configure your Google account on the phone; find it and sign out. That'll help, though I am not sure from personal experience how much battery it really eats up.
The screen is commonly the biggest user of battery life on these phones percentage-wise. This shouldn't be an issue. The absolute best thing that you can do to increase your battery life is ensure that you're always in an area that is getting a good signal, be it wifi or 3G. If you're often in an area where you're getting barely a bar of 3G switch to wifi if you can or, if that's not an option, get an application like JuiceDefender that will manage your wireless data for you (i.e. turning off your radios when the screen is off, scheduled syncing, etc). You do NOT need to use JuiceDefender, nor do you need to turn off any autosyncing if you have a good signal most of the time.
Turn off 4G when you're not using it. GPS doesn't hurt to leave on as long as you're cognizant of what is using the radio. If you leave GPS on, make sure that the little satellite indicator isn't running all the time (the indicator you see when you open up Maps, for example).
While I don't think it's necessary, you can go through and turn off autosyncing on apps, such as Twitter, FB, etc. At the very least it's a good idea to be aware of which apps are constantly connecting to the network. I let Twitter, FB, and Weather stay updated and have no problems. Again, the key here is to not be in an area where your radio is straining to push and pull data.
I can tell you from personal experience that bad signal strength has been the worst thing for my battery. Once I realized this and took steps to remedy it, I can easily keep my phone running through the day with moderate use and plug it in with more than 50% of the battery.
Hope this is helpful.
