Upgrading the battery will not burn up your device no matter how large the battery is. Even the ones that require a hump will not burn up yer device (well unless a drastic short or something occurs, but the same would be true of any battery).
Gtalk is just another method of texting and is a free google service provided if you have a google account and an android device.
If you are not using the full range of google services services on your droid, then you are barely tapping its potential. However you are not alone. VZW reps I talk to look to me with deer in headlight stares when I ask them why I have lost latitude integration with gtalk, both are very core google apps on google android phones and they themselves are using and have no clue.
Suffice it to say if you are using Bing as a search engine, and Yahoo or Hotmail (or anything but gmail) for email, and VZnavigator (or anything other than maps or latitude) for GPS. Then you are hopelessly misled.
Google made Android for its services. Its services are top notch and free. There is nothing better, use them.