Regarding the one-button mouse:

If you hold command (or is it ctrl? I'm not on my Mac right now), and then click, that's the same as a 'right click'.

Also, you can plug in a standard 2 button mouse, and the Mac OS automatically supports right clicks. There is even a control panel option to disable the trackpad when a mouse is attached, and to swap the right/left button functions.

As far as a three button mouse goes... I never tried it.