Shared Calendar with iCal option?

Administration is on a major push to provide additional communication with parents and students. Part of the request I have received is to have school calendars that multiple staff members can add items to and edit as well as have that calendar available to be used as a iCal or web calendar. I have seen reference to Resource as a possible options. I am rather new to GroupWise so am unsure if this will work.

I need the calendar to do the following.
1. Have staff member capable of adding and editing calendar events.
2. Publish the calendar to the web site for the public to view.
3. If possible have it be a iCal subscribed calendar for those members of the public that wish to do that.

I can also see teachers wanting to publish calendars they have to their personal portion of the website the school has. Is this easy to do? What are the limitations they would run into?