Well, it's a rather open-ended question about the future. I might do almost any of the above (pretty much everything except the world map to get things started) if (a) I have the time and (b) the project interests me at that time. Until the world takes on some form, it's hard to pick out a part and say "I want to work on that!" Maybe if this proposal had something more than "a world" to its definition it would be easier for potential participants to gauge their interest. Don't assume everyone has been following the threads that led up to this either.

Is this a science fiction or fantasy world?
If science fiction, how realistic and how high tech?
If fantasy, is it a round world, a flat world, a hollow earth, or maybe something more exotic?
If fantasy, what range of magic is suitable? Are there active gods and, if so, of what kind?
What unifying themes will tie together this patchwork of creativity? (If none, then what overarching reason will the world have for Dark Doomland of the Angst-Ridden Vampires lying in close proximity to Happy Sunshine Teddy Bear Valley?)
In short, what's the very general framework within which someone would need to work on this world? Without some constraints, you'll get chaos or logical flaws ("Why hasn't the steampunk wizard empire with the martial arts schools of awesomeness conquered this area of rich resources with stone age primitives inhabiting it?"), and whatever you choose with get some people's imaginations going and turn others off.

But lest this sound negative, let me conclude by saying there is a good chance that "If you build it, they will come." Once the project actually gets going, once it is real, it will be taken more seriously, and a more developed form will create more places for people to start building their own creations off of the established roots and actually be working on the collaborative world, rather than creating something and then trying to wedge it into the mix. Working on "a world" isn't exciting -- most of us are already doing that; once there is a particular world developing, there is something to be enthusiastic about.