it is always wise to have a look around before actually starting into things. For your requirements, it looks to me as if you are rather looking for a blogging system than a CMS (Content Management System), at least your feature focus suggests this.
1) Definatly, WB can do that
2) The standard news module allows for that (categories) and is capable of beeing used multiple times in 1 installation
3) The pages in WB are build on that kind of structure. You add a page, automaticaly the menu gets this data from the DB and displays the link in the menu (depending on the visibility settings of that page)
4) Section are always displayed in 1 content block. What you mean are the different content blocks that you can define and use. Theoretically there is no limit in numbers of blocks (or columns) than dictated by the usability ...
Have a quick go at the System (1 page Installer) and then decide. That's what I did. There is a demo available at www.opensourcecms.com
which might help you deciding.