anyone familiar with MAME?

I have a few questions, maybe someone could point me towards a help file? or just answer directly, 1st question; is there a way to change the controls, i know how to switch to the mouse using the default options/controls menu, but I just want to change the button configuration. 2nd question; Is there a way to change the colors of certain in game objects? example, in Metal Slug, i've seen pics on the internet where they spray red blood when hit, but in my game the blood is white, can i change that? "Hey Beavis,huh huh, pull my finger!"