I sometimes need to exit the full screen and minimize it to check the wiki, but how to exit full screen?
Do you mean switch window mode? The default command in most games these days is "Alternate + Enter" Keys. This should switch you to Windowed mode. If you meant simply get off the Fullscreen window onto another then the command is "Alternate + Tab" Keys. This is universal across all Windows systems to my knowledge.
If those don't work, holding "Ctrl" and pressing "Esc" will bring up your start menu. This will automatically switch EQ2 to windows mode.
I've never liked the delay in switching in and out of fullscreen, and have always been annoyed by the window border when running the game in windowed mode. I built a utility so that I could play the game in windowed mode while still having it take up the entire screen (some games refer to this as something like "windowed fullscreen"). http://www.eq2interface.com/downloads/info5106-MakeWindowFullscreen.html As far as performance goes, you're still running the game in windowed mode, but it's a nicer experience when switching between the game and other applications.