as far as details go... you do realize that a pc is meant for only one user right? i know of routes where you can use two mice on a screen but generally speaking it isnt the best route to take.
it sounds more like you are wanting a central server and individual terminals which are connected to individual mice and keyboards. the trouble is... they are often slow and underpowered. the exception to the rule would be the ones ran by supercomputers. for your operation one pc could probably run it, but dont expect speed.