I have noticed that while hooking up arcade buttons to the GPIO set on the model b board that along with the joystick I should be able (by assigning certain GPIO pins to ground) to connect 7 other buttons with individual grounds. However if I could attach multiple inputs to the same couple of ground pins (probably something rough like soldering the ground wires together) I could connect something like 11 buttons. Would it be likely for this to cause an issue with the input buttons? I am very new to this sort of thing, thank you for your time.
you need only 1 (one) ground pin for does not matter how many input buttons. there's absolutely no reason to use any other pin as a ground as long as you have one already used.