Pretty miserable battery life out of Android phones... If they're that bad on just video and audio playback, imagine how bad they are when using the radio for phone calls or network access.
My Droid X has very good battery life. It almost last as long as my iPhone, and that's with full multitasking and over 10 widgets actively running at all times.
No, but it had 4.2.6 and there wasn't anything added but Mobile HotSpot to it. There was really no other advancements in it. So, for all intent and purpose, it's the same thing really.