In case i want to seal this arcade box, does raspberry support so many controller inputs? (2 USB-joystick-button controllers, 2 normal USB controllers, 2 light gun controllers and 2 wheel controllers?)
Not sure on the light gun part but I would assume so, I use the ipac (mini) as well with sanwa joysticks and gold leaf buttons from ultimarc. I've used the inexpensive stuff on amazon also but nothing compares to the ultimarc IMO. The only thing with the sanwa's is going from 8way to 4way switching for games like Donkey Kong as the switching is under the panel. I tried using other joysticks that switch at the top and just didn't like them (mag-stik being one of them). I did get the sanwa working with a servo (servo-stik) for auto switching however my control panel did not have room to fit the servo... I used a toggle switch to move the restrictor plate. You can also set the rom bootup to change to the correct setting but I opted for a manual switch.
I use the arcade sticks for mame games, and usb wired xbox360 like controllers for nes/genesis etc. Some nes/genesis games I use the arcade sticks as well, Works great either way. I don't remember if I ever got genesis 4 player games working with arcade sticks and usb controllers together, IIRC I had to use 4 usb controllers was something with the multi-tap in genesis but I only have 1 friend so it's not a problem normally lol.
You will need a powered usb hub as you wont have enough ports for everything.
MDF is what I used for a small 2p bartop, going to do a 4 player pedestal next using MDF again.