In SpriteTool, if you insert sprites at 00, 001, etc, do they overwrite already existing sprites in the ROM? Are there adresses that are empty that you can write to? Also, how do you put a sprite into the "Custom Collection of Sprites" in the Lunar Magic add sprites window?
EDIT: Also, are the ExGFX for the sprites inserted in the same way as the normal ExGFX?
First, I would suggest reading the readme. It answers all these questions and you should ALWAYS ALWAYS ALWAYS read it anyway.
Sprites are not overwritten- they're their own set. See my thread in the tutorials forum for a tutorial on getting the custom collection of sprites working. And ExGFX is inserted just like that, yes, but on SP1,2,3, and 4 instead of the FG and BG ones.