Getting html into the headers and footers is no problem.
I did read the instructions, but didn't quite twig what the Media / NoteID was all about. I sort-of got it working, but I still find it confusing. I'm not entirely sure what the design intends. Maybe I'm a bit slow!
The bit I don't get is the top 3 drop-downs in the dialog: Home, introduction, contact. I could only choose images in the drop-down lists, even though I experimented and set up notes and other stuff too. I added external html text files, could choose them, expecting them to be picked up on the information page, but nothing turned up in the html source.
I wanted to include a gif image of my email address for the contact page (so spam robots won't spot me), and although I could choose it, gramps generated a bad tag. The tag contained the correct img filename, but the path was missing. I guess there are still a few bugs.
Anyway, I moved the email.gif into my page footer, and for now I'm a happy camper.