There's a lot here, so I'll try not to be too unwieldy with my thoughts.
@Grimjack: I think a pretty apt example for us is DeviantArt. They place a lot of trust in the community to adhere to their etiquette policy and self regulate. I'm in agreement with you and Patrick that I wouldn't want to limit or stifle creativity with regard to customization.
Copyright and fair use will be an issue. We want artists to get credit for their work, and we also want creativity to flourish. @Bengali and Grimjack, we'll likely have to have a formal DMCA takedown process. Leaving copyright to the community might get the company in hot water (though, we won't be hosting any of the images--still, I bet Disney, for example, would try to sue us if some players turned Volition into a Star Wars CCG or something). If we do take the prudent approach, it'll be important to be as transparent as possible when removing art. I don't know how to do this one democratically, except to be honest as possible.
@sprocket314, Volition may inherit some mechanics from The Spoils, as well as some of the humor and absurdity, but I think Patrick and Ken are designing this to be much less outrageous. The sets that we launch will be appropriate for younger players--13 and up, let's say. But, as with any democratized system, it's wide open to, well, being gamed. In my opinion, the three primary categories of concern are prohibited content (obscenity, abuse, etc.), restricted content (nudity, profanity, etc.), and discouraged content (stupid stuff that detracts from the game: e.g. spam or art that makes a card look similar to a different card). Grimjack pointed to the difficulty adjudicating between these categories. All communities are going to struggle with this one (as we've seen with Snapchat, Facebook, Reddit...). My argument would be to rely heavily on the community to flag content, and we give players the tools to filter accordingly.
And, the other point sprocket and grimjack raised might be rephrased as: What kind of community do we want to encourage? This is difficult. We really want this to be a decentralized game. I sometimes use the term democratized. But, I don't know if I'd be comfortable if it was dominated by a particularly annoying group, especially at the beginning when we're trying to build critical mass. The economic model for the game might be laissez faire, but should that extend equally to the user-generated content? Can we justify balancing the health of the entire system by sacrificing a little freedom of speech? Should we merely emphasize and advertise our values, but try to stay out of regulating behavior?
Anyway, this is one of my favorite aspects of the game, as well. It has opened up a lot of questions for me, and it's been extremely challenging to have to think through the politics of it all. The questions I raised aren't rhetorical. I'm very interested in hearing what others think.
The one thing we do have going for us, as Patrick alluded to, is that this game is meant to be played in person. If a player wants to test the boundaries, then they will have to accommodate the responses they might receive. IRL problems...