jdslay is right, the only and best way to set up calling difrent extensions is by using a hunt group as the Atendant DN and program the Extensions you want to ring as members of the DN
now, to get the messages from the attendant extension to the administrators phone, the best way to do this is by adding a unified messaging license to the CP100, and programming the administrators email client (Outlook, Outlook Express) to login and retrieve those messages. this way, the operator will have no idea that the messages where already checked (the administrator can 'Mark as Unread') any message, the administrator can also save a copy of the message on his PC and share with anyone who has an email address.
if you want to implement that, give me a call, I can sell you the UM license, and teach you how to install it on the CP100 and on the administrators PC.