If you enter your tracker on SSA.org, you do not need to register on glideport.aero. However, if you do register, once logged in you get a lot more functionality, e.g., from simple things like updating your tracker and that taking effect immediately, uploading your photo, subscribing to "follow" your buddies so that you get an email notification when they fly, all the way to uploading your IGC files and seeing them in hi-def.

The GlideTrack app description in the app store contains instructions how to get going. The effect on battery life would be minimal if you already run other apps. GlideTrack does not need continuous cell phone coverage, it assumes the cell coverage is poor and it is designed to be tolerant to it. For more info about GlideTrack see https://github.com/glideport/GlideTrack

Pedja