Risking to state the obvious, you will also need a hub or switch (unless you simply connect to existing ship LAN).

As for removable drives, I think there exist IDE drives in 'drawers'. You install a 5.25" bay into the computer and connect it as you would a standard IDE drive. Then you plug in the 'drawer' with the 3.5" drive itself. I'll have to ask a friend who sells this kind of stuff (the last time I actually saw them they were 300MB EDSI drives...).