Well, green means the member is online, and red means that the member is offline. Haven't ya ever tried to place your cursor right over it? It says just that
I really don't know why they were closed. Probably because the mods thought we were spammming or something. There's a thread Statikk HDM has started a thread about it
here.
Finally, you can find the Art of Oddworld book
here. As for the price, it varies.
EDIT: Also, this belongs in Forum Suggestions and Help, since two of the questions aren't concerning Oddworld. Someone should probably move this.