My toons are at 85 now. But I haven't done much of questing. I leveled them through dungeons. So I can go back and do some of those quests (most of them are sooooo boring )
So if i down bosses from wrath or TBC raids I get guild XP too ? But not as much ?

There is no way I am inviting "noobs" into the guild as that is the exact reason I multibox. I limit the human factor to a minimum, 1 person to be exact !