Actually you need something more important than that.
You need a team LEADER. Someone who is totally focused on the project at hand.
If you're not willing to put years into it, then don't apply.
Once you have your "Rock" to keep on people and organize things you need a story, or you work on teh models you think will be in the story: A writer and modelers/texturers.
Voice actors are the LAST thing you need, it's audio candy for an almost finished mod.
Then if you decided you want special features not in the newest build, then you need coders.
You get the point. Anyway, without at least ONE indivudual to keep things grounded mods tend to fly apart, thigns get lost or overlooked, and no one can say exactly what's going on.
A team leader should have a back up and a third, they should have equal access to the latest files, should the worst happen...
Good luck with your effort!