Re: multiterminal setup, dual X & dual controls
A single videocard can only run one Xserver. It can be a little confusing that a card can output to two seperate X screens but that all happens in a single instance of the X server. (one X server can only use one mouse and keyboard)
If you want multiple Xservers you need two videocards. The second Xserver can then use a different mouse not sure if it can get a different keyboard. Using hacks this was possible in the past but not sure what the current status on this is.