the lamp in it is a 12v it says when usually they are a 5 but if it is 12v then the yellow wire on your pc's power supply molex is a 12v and if it is a 5v then you would need to use a red wire instead of the yellow.
as for your coin mech switch's the outer post that is single and not alighned like the other 2 is the ground and the center post of the 3 is were your signal/+ goes
dunno what your using to interface the switchs with the pc though till you explain how your planning that.