I think we can help with user input on this thread.
The 'genre' component (call it tags, genres, whatever) is a total mess. Normally you'd want to narrow down the options for main categories (genres) and probably even limit the number chosen for a given story. Then you can allow the author to go bonkers for refined categories (tags).
Rather than you having an unholy crapton of work retrofitting existing stories into a new framework allow authors to relabel their stories (within the new scope) and basically limit your work to moderation so that you just have to push the OK-button to have a the changes go through.
To further enhance the feeling of main categories (genres) actually run with sections and include the associated forum in that section. Ie the collection of superpower stories directly shows the topmost threads of the superpower subforum with a link to open up that entire subforum.
Within scope of the superdesign (main design for WFG) allow for subdesigns so that users visually see where they are in the structure. Such a division by definition needs to be decide in advance. Ie, do you want to run with a reader / author main division of the site, or do you prefer division by genres, or, etc, etc, etc.
Should TWF be integrated in the site?
Do you want a section with information on the most common publishing platforms?
Is it a good idea to display clickthrough statistics (and implicitly create popularity lists given this site as the originator from where readers click to the real stories)?
And there are probably numerous other suggestion users of WFG could come up with, out of which you pick and chose among those that tickle your taste. In the end you and eventual other people who put in work to keep this place running decide what goes and what does not.