"Can you set up a calendar that has no author? The problem we have had is staff have set up a calendar and then have left the company and then we can't edit the calendar."

All calendars must have an author assigned to it. This how you designate who the calendar belongs to. If your within an exchange environment the you should have a systems administrator that can change the users password to access ther account to edit the calendar.

"Can you transfer between a personal calendar and a shared one easily without manually copying it over?"

This questions is puzzling. Within your outlook 2007 client do you not have access to the Shared calender? If a calendar has been shared, the author has to just simply grant you the proper permissions for you to view this within your calendar view. you will see your main calendar then any shared calendars.

Hope this helps.