I've used d-i quite a lot with automated installation, and I know the
Skolelinux people are using it as well. Customizing d-i for automated
installation is quite easy -- debconf preseeding takes care of almost
everything you need, since most of the bugs related to automated installation
have been weeded out by now. (That is probably what you're referring to in
your first option.) I don't know if there are any easy ways of automating
this (I do it simply by building my own disk images and include the udebs I
need together with the database), but it should be quite easy writing up a
mini-HOWTO. (I might do this when d-i is getting ready for release.)