Hi,
I'm Alex, PHP developer from Lithuania.
Your idea sounds really interesting and cool - never heard of such page on the internet. Do you know if there are any reference websites? Anyway, I assume it would be very important to make authors profile and visitors profile as well as book page (for suggestions, plot and discussions board). So lets say you need:
1. Social channel registration/login
2. User profile
3. Publish a plot/scenario of your imaginary book. With title, description, category (romance, horror, action, drama, etc)
4. Search field to look for new plots or plots based on category.
5. Book page where you can see all suggestions, post your suggestion and see the overall progress of the future book.
6. Possibility to order newsletters on exact book page (if new comment was added or something changed to the description, etc).
Whats more?
Anyway, this kind of web sounds great. :) I suggest to use WordPress as I have extensive experience with it and can easily help you out in the process of development and anytime in the future. Let's have a chat to proceed and discuss more deeper.
Thanks!
Alex