I buy $10 PC speakers from K-Mart. They are just as good as what most arecade games came with anyway.
Also, I know you keep SAYING you have read everything, but it is obvious that you haven't.
Let me clarify a few points.
A control deck is the main component of a Nintendo, which is what they had before Playstation (for some reason I am betting you like Playstation). It IS NOT a part of an arcade cabinet. You keep talking about the "consoles" and "control decks" and I can' tell what the heck you are talking about? I THINK you mean control panels.
A roller is something you use to apply paint to a wall. It is not a part of an arcade cabinet. I THINK you mean a trackball, but you could also possibly mean a spinner, or even a Major Havoc controller.
Second, it seems to me that you are jumping into this all sideways, by planning on choosing the ultra-expensive option of building a cabinet instead of refitting one, but then at the same time planning on using mouse hacks and joystick hacks for interfaces.
I can't figure out your exact computer plans, the only part of them I saw mentioned a hard drive large enough to hold Mame 20 times over (or 8 times over with the hard drive games). The only reason I mention this is because you thought a coin door was a waste of money.
Also, where did you get the idea that arcade games have "screens with holes on the sides for venting"?
Basically, you REALLY need to research this more, before you end up with a $1000 monstrosity that looks like a turd, doesn't work right, and will end up in the dumpster.