I think the idea of collaborative animation is interesting (knowing nothing about the field), but remember that for every successful open source project there's probably 20 failed ones. Most of them start with one person doing all the work, until eventually other interested people come along (or don't) and start contributing little (or big) things here and there. If you build it, they won't necessarily come.
Scoop already allows people to upload files (if enabled.) That's already done for you, but it's not enabled on K5 or (AFAIK) DailyKos. You can try looking at hulver's site to see how the interface works.
What do you mean "there would need to be different ratings, user info fields, postings"? janra's working on making the user prefs more customizable which I think would also do what you want for the user info, but that probably won't be in any release until sometime after 1.0. You can divide the site up into as many sections as you want for stories, and I think that would be able to handle the "different kinds of postings" if I understand what you mean, but if you're talking about comments then you're out of luck. I'm not sure what you mean by "different ratings," so I can't comment on that.
Finally, do you see toonex as being a place for people to post their works in progress and then have others comment/discuss them, or do you see it as being a place that others will modify the work if they see a way to improve something? If the former, I'd say scoop is a good place to start, if the latter I'd say you might want to look into wikis.
