While you should check the requirements of any add-ons you buy, if you hope to connect all that stuff to one Mac you will need either a USB hub or a PCI card with more USB ports. I have a tower and an aversion to desktop clutter, so I got a PCI card that added three USB 2.0 ports and two more FireWire ports. So far no problems.
Bus-powered devices are those that get power from the power wires in the USB cable rather than having their own power supply. You can only have so many bus-powered devices on your USB bus before the limited current available is spread too thin. For a serious collection of gear such as yours, I'd recommend a more expensive USB hub that comes with a power supply, so it can help power the stuff on the bus.
Have fun with the Mbox!
Crikey