Janine.
Sure it can do this.
The OpenACS.org home page is an ETP page.
The way I use ETP is to make a "page" for each navigation element and then include the contents on the "page" in the other templates. The code for the boxes on the OpenACS.org home page is here:
http://dev.openacs.org:8000//cvs/openacs.org-dev/www/templates/widgets/
It would be nice to use a portal-like system to add chunks to pages, but we aren't quite there yet.
I don't think adding/removing template elements is possible with ETP currently.