Help approach

Hi all!
I write to see if anyone can help me out in the approach: what use cases page, custom post type, category … in the following.

The idea is to take home a menu with the following options:

1. About us (+ sections)
2. Areas: subarea 1, subarea 2, subarea 3
3. Projects: to enter to display the latest projects from all subareas
4. News: it will display the latest news by date of all the subareas
5. Contact: simple form

The issue is that upon entering any of the subareas, these will have its own menu:
Example: within subarea 1 we have:
1. About Us
2. Projects: displays only projects subarea 1
3. News: displays only news subarea 1

The question is: what elements should be pages you consider that, what custom post types, and what category, as discussed above?

Thank you very much in advance.