Educational questions... I learned a lot seeing what the possibilities were.
>> group members to have the option to opt in or out of these notifications, regardless of their group email status. <<
Don't think you can get there from here in google groups. The only
option I can think of would be to set up calendar email notifications
to yourself, then build an email filter that would forward those
notifications to your group.
You might need to set the calendar up under a different account to
prevent notifications from your personal calendars from being sent to
the group.
>> I'd also like to create a calendar to share with the group, without having to share it individually with every member <<
The only way to do this (easily) with a google calendar is to share
the calendar _publicly_
When shared publicly, you can get an HTML url for the calendar that
you can then post to your members who can then go to the calendar
using any browser, but the calendar will show up in google searches...
not necessarily a bad thing for your group.
It is also possible to share XML and ICS urls to a google calendar
with the group without making the calendar public to the world, but I
would guess that it is unlikely that your entire group would be able
to use these links without help.
Note that other forums such as yahoo groups might have better
options... yahoo had "events" but they seem to be broken at the
moment.
Hope that this information is helpful.
Beverly Howard