Here is about how to share your calendar with others:
- You can click on the Sharing link, which is available on the top left of the page.
- If you only want to share your calendar to a limited sets of people, you can set as "Friends can view my calendar; Special Friends can also modify my calendar."
- Add your friend one by one to the My Friend list
- Until now, you have granted the permission to others to view or edit your calendar
There seems no public calendar search capability so your friend have to know your Yahoo ID to access your calendar.
In general, the functionality provided by Yahoo!Calendar is limited. you cannot easily find whether you can show both friends' calendar side by side with my own calendar.