The following system is planned : There should be one main notebook, to which are connected several displays with keyboards to offer for several persons chat opportunities. This chat should be projected with a beamer on a screen.

As I'm pretty new to Linux, I have several questions:

1) Is it possible for one computer to get at the same time different inputs from different persons and to process the inputs correctly? How could this be realized? Is x.org an adequate software solution?

2) How could the whole system being realized? What should be taken into account when buying the hardware?

3) Are there any Linux-specific problems with connecting to a beamer which are hard to manage for a newbie?

The whole solution should be as easy as possible.

if I understand you correctly you want to set up a chat server

chat server http://sourceforge.net/projects/freecs/

your going to need a desktop with a display controller for each display
at best a laptop can handle 2 displays and I have yet to see a laptop do duel displays
I have seen them out put the same thing both displays but never different things on the 2

some usb keyboards and some usb mice and at least one usb hub

and this would be a beast to configure I think it would also have to be reconfigured each time it was set up

the easiest way to do it would be a network (several laptops) not one box to handle every thing

You could try these: http://en.wikipedia.org/wiki/Multiseat_configuration and https://help.ubuntu.com/community/MultiseatX

@sxqm what do you mean by beamer do you mean a projector if so then it's just like a monitor

looks like were going to assemble an answer for sxqm