There is no officially posted E-Mail for this person at this time. NOTE: A suspect e-mail address was removed from this answer.

No. Certified Mail usually is physically mailed from a post office. If you have a digital signature (subject for another question), you can digitally sign an e-mail message to confirm that you were the person who sent the e-mail. You also can request delivery notification with most e-mail programs.

It means carbon copy. If you want to sent an exact copy of your e-mail to a second person put his or her e-mail address in the cc box.

If you have an email address and the other person does.

no. you have to create your own yahoo account. If you know someone's e-mail address and password you can ask them for permission to use their e-mail for something, but you cant just log into a random person's e-mail address. Unless you hack it, which is illegal.