Unfortunately, I think Steve is the only one with a sound operational knowledge of the Groups feature. You already have more experience with Groups than I (or most of the rest of us). I know Steve has written some prior posts on this topic in (I believe) the Moderator's forum which may be worth rereading, especially if you missed them. I believe he also covered the method by which interested parties can elect to subscribe to a group at which point the designated Group Admin must then either approve or reject their subscription request.
My basic operational knowledge of their function is that groups are meant to be a mini-forum that, while viewable by all members, only select-invited members may actively participate (comment) in. The purpose being to facilitate the coordination of various functions, club memberships, local get-togethers, etc. Namely, topics that are of typically very narrow regional relevance (e.g. a lunch group) or the coordination of very specific tasks (such as the upcoming picnic).
It could be awhile before a real How-to is written. Steve and I have both been working much greater than full-time hours pretty much everyday since January, so we are both getting a little burned out at this stage (Steve probably even moreso than I) and there is still a rather overwhelming amount of work to be done on this site. I don't think either one of us have spent more than a few hours, total, in our shops since the upgrade.
I mention the above so that everyone understands if some requests take awhile to fulfill.
