2) I seem to notice that spamd is the thing that creates the user files, rather than spamc -- if I still wanted these config files generated, for backwards compatibility (my plan is I would date-parse them on a cronjob and insert any modified ones into the SQL db with a setuid perl script), can a switch be added to spamc to do it instead?
I think your best option here is to do a mass move of your users prefs files to the SQL db then provide one of the many web based solutions for changing those prefs.
One of the best I've found is a plugin for the SquirrelMail web-based mail client:
http://www.squirrelmail.org/plugin_view.php?id=167
Mike Jackson
CMC Tech Support
