“Cascading” posts using WordPress as CMS

Using WordPress as a “true” CMS (not a blog engine), I am trying to set up a web site for an institution. My plan is to have each different department appearing on one post, with a short intro and “excerpts” to sub-departments.

Going one step further, I could even have an “About Us” page that shows a short intro and excerpts to all departments.

I have the feeling this can be done without external plugins, only using WordPress loops and templates. Would anybody have pointers on how to do this?

Many thanks in advances and my apologies in advance if this is the wrong section.