Category, Section and Tag help

[justasiam]

After much discussion at vbulletin.com, I have finally begun to understand the difference between sections and categories.

Categories:

• Articles can be assigned to multiple categories, but NOT multiple sections.
• The order the categories are listed in are determined by the order they are created. They cannot be re-ordered.
• Categories have no configuration options.
• When using the category widget, all categories are displayed, regardless of the section assigned to wherever the widget is place.

Sections:

• Articles can only be assigned to one section. Unless assigned to multiple categories that are in separate sections.
• Sections have a wide variety of configuration options.

If the information above is correct, I have a problem.

• I have articles I want assigned to multiple categories. This is not a problem.
• I do not want a fully expanded category list to show up on the "left-hand" menu. This is why I use sections there.
• I do not want a expandable section list on the "left-hand" menu (eg. section, then sub-section, etc).

What I would love to see is as follows (In a perfect world):

• The "section" menu on the left.
• Even though I have sub-sections, I would prefer if they were not available from the left-hand menu.
• When a section is selected, at the top of the content for the new page, I would like a list of all sub-sections for that section only.
• If I select a sub-section, the new page comes up with all items in that sub-section and displays any sub-sections at the top.

Can this be done? Somebody suggested the use of tags, but I don't understand how to set tags or apply a link to a specific tag at the top of the page.