Trackball and Spinner panel help...

[dema]

I'm building a cabinet with rotating panels, and on one of them I want to put a trackball, a spinner, and obviously the buttons. I was going to put a few mouse buttons in place for the trackball, but I wasn't sure how many additional buttons I'd need to install to cover MAME and PC games. My questions are...

How many buttons should I install on the panel in order to play trackball and spinner games for MAME? The three mouse buttons, and then how many other buttons?

And secondly, how many buttons do you think I'd need in order to play most PC games? I could put as many buttons as necessary on the panel but I want to make sure that the total accomodates both PC and MAME games. I don't want to put a bunch on the panel and then find out I only need three of them so I'm using a panel with a bunch of useless buttons. I'm looking to play things like Tiger Woods golf, and some other trackball-based games as well.