A: X window is a Graphical server which lets you run programs in graphics mode. In linux there is a famous XFree86 X window server which is free and it is based on Xconsurptium. But there are also some other commercial servers like AcceleratedX and MetroX. They have just some better card support and sometimes they are faster.
A: If you have XFree86 3.2 or newer there is a graphical setup which can be invoked by XF86Setup. Then it is really easy to install your graphics board. Just folow the instructions. If you have XFree86 with version < 3.2 you need to run xf86config, which is text based. As for Accelerated X you have Xsetup and for MetroX you have setupX. Everything depends on the X window you have.
A: After configurating X-Windows, just type the command "startx". If your card supports more than 8bpp (2^8 = 256 colors) you can run X window in 15,24,32 bpp too just invoke startx with some more paremeters. So an example if you wanna run X window in 16 bpp (65k colrs) just run " startx -- -bpp 16" and you will be in 16 bit color mode and no more problems with color loss :)
A: Most of them can be run from a Xterm as normal programs, but as people are lazy =) they figure out that they can use buttons to start some programs. Well just everything depends from the window manager you use.
A: Window manager is a program that makes your look and feel in the X window GUI. It is a program, not that complicated, but just with the esential to make your life eazyer. It does the menus when you press the mouse button, it does the borders around the program,... If you want to costomize it you need to edit the system resource file for the window manager. All users can have it customized for themself and the file should be in the users home directory. As I use AfterStep I am going to describe how to configure it. As AfterStep was developed from fvwm it has lot of things that are edentical or equal to the fvwm settings in its system resource file. First all the files needed to run Afterstep are in /usr/X11/lib/X11/afterstep directory except afterstep the executable one which is in /usr/X11/bin. The main configuration file (for whole system) is in /usr/X11/lib/X11/afterstep/system.steprc. If you want to make a user defined one just copy this file into your direcroty and rename it into .steprc. And now something about customizing the window manager. Open the file with an editor (jed, joe, emacs, vi...) and when you are in just follow the instructions and you will get a beautifull window.
A: Some window managers supports virtual screens. One of them is fvwm and they just make another area in the manager so you can have more windows open without minimizing and maximizing them.
A: Just run "xv -root -quit bitmapfile.format"
A: Everything depends on a window manager...But there is a script file where all X window programs are lounched at startup. the file is normally in /etc/X11/xinit/xinitrc or /usr/X11/lib/X11/xinit/xinitrc . Just edit the file and you will have the program started every time you start X windows.