I have made a mistake when adding birthdays to my contacts. But cannot find any way to delete them. And I seem to have Chinese years/characters for some of them.
To remove a Contact's birthday, you need to edit the contact's information. Go into your Contacts list, click a contact, click Edit, scroll down to Birthday and click the red circle, then Remove. You will need to do this for each contact.
As for the Calendar issue, try this: Settings > Mail, Contacts, & Calendars > Alternate Calendars > click Off