Dynamic menus based on taxonomy -- possible?

Hi all,

I'm new to the Drupal community and all stuff though I think I found out a lot of stuff pretty quickly. I managed to apply my own design to the CMS and to set up the basics. I also think that, to some degree, I understand how taxonomy works. Moreover, I found the views.module which appears to make a lot of things even simpler. Nonetheless, I am having problems with custom menus in Drupal.

Please let me explain the situation so you get a better idea to eventually get me to the right direction. Let's assume I have a taxonomy vocabulary called "main categories". It includes the following children:

category one
-- subcategory one
-- subcategory two
---- sub-subcategory one
category two
category three
-- subcategory xyz

Is it possible to now generate a dynamic menu that is based on these taxonomy terms? I actually want a custom main menu to be displayed on every page with ONLY the direct children of the vocabulary. That means I want the menu to look like this:

category one
category two
category three

Whenever I add a new child to the vocabulary now, I want it to be added to the dynamic menu.
Next thing is to achieve this: When clicking on "category one", I should get a custom page that has another menu (specific to this category). This menu should, naturally, include all the children of the "category one", that means the sub-menu should look like this:

subcategory one
subcategory two

This should be dynamical as well. Is this possible with little effort and/or no modification of the core? Moreover, would it also be possible to only show menu items (children) that actually do have at least one post already?
I thought of the views.module but it actually provides only lists of NODES that may or may not be based on taxonomy terms. What I want to achieve is somewhat different though.

Thanks in advance.