After looking at the Mod you linked, I came up with this idea of modifying the showgroups template, because the mod you linked is a major add-on with db changes and all, and I don't think it is necessary in order to accomplish what you want.
The right direction I think, is just as you have described - modification of the showgroups template to call up the things you want for each staffer. And I bet most of it can be called from the datastore instead of the db itself. Making this a far more simple and user friendly add-on.
[MENTION=1]Ozzy47[/MENTION] would know alot more about that than I, however.