and it allows the player to transfer to diamond and pearl again
Sorry for the delay, but in order to make sure you don't strip the screw, i would suggest buying the Tri-wing screwdriver. Besides you never know when you may need a Tri-wing in the future.
No, replacing the battery doesn't erase saved data. It just starts up timed events again and gets rid of the "dry batter" message.
Yes I know it is the original, but it is not the point though, it is the principal of just putting it back together the way you started. The CR2032 is a big battery and i tried it in my my own copies of Ruby and Sapphire and it bulges the case but the case will go back together and fit *snugly* into a GBA slot and it does work. As stated in the guide try to use a CR2025 or a CR2016, they should fit better with the case.