As long as your book title doesn't start with an "A" (because that means your book will automatically shown as the first option), then it's unlikly others will accidentally add to your book. Even if it happens, it's still very easy to correct (just click "outline" when viewing a page).

I'm more worrying about that editors can modify other user's work, because I think most people don't want thier stuff to be modified. Later on, I need to find a way to restict it to edit their own work.

As for publishing, publishing in print is a very different world. Here's more like a hobby thing. You can practice your skill here, build up your readership, and later on you can find an editor to publish your work in the print world.

The publishing forum is more of a tips to publish your work in the print world (like sending query letters etc).

I think that as long as zen resticts the editors to a few, trusted people, I think that it will be alright. Perhaps you could have a group of responsable moderators that wouldn't have the power to change anything unless at least 2-3 people are offended enough to write to a trusted moderator or zen/nil.

I think that most of the people that are regular users at the abandoned forum respect eachothers onions and artistic licence. I personaly trust the editors not to edit my work unless is was extreemly insulting or profain. But that is just me. Just in case, It might be wise to save a copy of your work not on the site.