Your email address will only be used for password reminders, and
any system alert messages you've opted to receive. You don't have to give an email
address, but if you choose not to, you won't be able to retrieve a forgotten password.
Do you want everyone to be able to see your XP and the chores that you've done (so that
you can show your profile to other people), or would you rather restrict access
to just the other members of your party?