The Google Apps Sync for Outlook tool did a good job of migrating your calendars from Zimbra to your Google Outlook profile, but it stops one step short of creating those calendars so you can see them on the web when you access Google Apps.
To remedy this, you can simply move these calendars up to the server:
The next time Outlook syncs, you'll be able to see that additional calendar up in Google Apps.
If you have received an email that another account has granted you access to their inbox, you need to click on the link to accept the share. Once you've done that, here's how you open the inbox in Outlook:
Those accounts will show up in your Outlook after the person has shared them with you. They may not show up until you close and re-open Outlook.