The email address you provide will become your EtherBanking ID and will be used for all future communications, including account recovery. Protect your email account like you would your EtherBanking account. Sign-ups using throwaway email addresses will be rejected.
Your password must be at least 8 characters long, but it is HIGHLY recommended that you choose a random, alphanumeric password of at least 32 characters. NEVER use a password for an exchange that you use ANYWHERE else, especially for the email address you sign up with.