David wants to know: "How far back in history will an Outlook\Exchange calendar go?"

It goes back as far as you want it to go. If AutoArchive is enabled, you can either delete or archive old calendar items as they age. If you are on an Exchange server, the administrator may have the server configured to delete old items using Exchange server's Mailbox manager.

To check you AutoArchive settings, go to Tools, Options, Other. To configure any folder to use different AutoArchive settings, right click on it and choose Properties, AutoArchive.