Blog notifications for the admin (like comment moderation, Likes, new subscriptions, etc) are sent to the email address at Settings -> General in the Dashboard.

Personal notifications (like comments on your post, subscription emails, and upgrade renewals) are sent to the email address at Users -> Personal Settings in the Dashboard.

See also > Issues Changing your E-mail Address > http://en.support.wordpress.com/email-address/#issues-changing-your-e-mail-address

re: frequency of receipt of posts from blogs you follow
Go to > http://wordpress.com/#!/read/edit/
locate "Get new posts by email"
in the dropdown menu select one from:
never
instantly
daily
weekly

Can you tell us what you're trying to do?

Julia