Yes, you create all categories yourself from within the WordPress admin dashboard, so they can be whatever you want them to be. (Note: the categories you see in the demo are
not there by default).
Yes, you can also create whatever pages you like to go in the main navigation menu, and pages assigned to parent pages will become part of a drop down menu such as what you see when you hover over the "About" page on the
ClassiPress demo.
You could do this with some custom coding. By default, there is only one blog though, and you are also able to create blog subcategories.
