I've developed two different content management systems in the past. One was for a major corporation's internal intranet, and the other for a large government entity. In each case, I used a database driven back end to store the content and manage the permissions. The database also separated the content by topics and kept it organized. Having said all that, I would have to say that it takes an awful lot of time and effort to do all that, but 10-15 years ago that was the only way to get it done.
Today, you can accomplish all of this with a good, well-organized blog. Wordpress, for example, allows you to add users with permissions who can add articles or posts to the site. You can categorize or tag each article, and you can even have the writers receive the comments for their own stories. I would not try to rewrite the wheel, because the progress that has been made with blogs makes it all so unnecessary.
As far as WYSIWYG editors, look at this site! If you scroll your answer box to the top, you can see what you are typing directly below it so that you can see what your readers see as you type it. You can see the hyperlinks, the bold font, italics, everything. There are widgets available for blogs that allow you to do the same thing. I think you will find your time much better spent trying to find a suitable template and piecing together a collection of widgets to provide all the functionality you need.