Pass value for "email" from Creator to Invoice & pass value to always allow Online payments [ANSWERED]

Pass value for "email" from Creator to Invoice & pass value to always allow Online payments [ANSWERED]

Is there a way to pass a value for "email address" from creator to Invoice.  Im passing all the mandatory values but email is not one of them.  If i use it a custom field, would I be able to map it to the email field in Invoice?

Also I want the a boolean value to allow Authorize.net payments for every invoice.  How can this be accomplished?

Lastly, once these two items are integrated, can I program Invoice to email the newly created invoice automatically upon creation to the recipient?