Advice for themes, modlues, and strategy to for this first project

The Project:
A site for kids to write their stories on line. The home page would have a new writing tip each week and a link to log in to be be directed to a work area where only they have write access. There they can make their own background, write their stories with pictures and text and/or upload PDFs, pictures, and teasers for stories they want to sell, etc. E.G. it needs to be easy. They could send e-mails with links to family and friends with links to their story. They must be able to assign their stories to pre-defined categories so people could browse the site by category, author, etc.

What I need:
What I need is advice as to which themes, modules, and strategy to use to support this first project that will help me get started on how to learn how to learn WordPress. Thanks!