Sorry--some of us have day jobs that don't involve spending our time posting on TWG.
I like the idea (since it was kind of one I was interested in doing a while ago.) A few suggestions:
1) SE is a good one to be in charge, since he knows a great deal about role-playing games. If he's going to be the one writing the fiction, might I suggest that he have final say on world design? Personally, I think it would be better to adapt the game from a good fiction world than try and make good fiction from a game world. (But I'm probably biased in this area.)
2) I really like the name TWIG. It's nifty. As for what it means, I like SE's first suggestion. Time Wasters (Insert random vowel sound) Guide. TW(i)G. So, the random vowel sound stands for 'Insert random vowel sound.' Like I said, nifty.
3) I'm willing to help out, but I'd prefer just in a referential way. I've never been good at collabrative world or storybuilding--I'm too deeply-seated in my own traditions, and am accustomed to complete control over my worlds. I wouldn't mind giving suggestions, however.