[esqueue]

The black tape on the cover is to display the orange. The reason why the battery isn't as hot is because it is simply larger with 2-3 times more surface area. That is kinda simple.

The plastic kinda works as a sound port for one of the speakers. If you notice the sound comes off of one side and is sealed by a rubber square while it travels to an exit port on the other side of the cover. Look and you will see what I am talking about. Press around the square and notice that it is rubber. The sound comes out, travels down the small port and exits the holes on the back. Removing the plastic definately affects the sound quality. I don't like the sound without the cover.