CubeCart Registration modification

On a CubeCart v3 modification required as follows: On the Account Registration page there is a checkbox at the bottom asking if the person registering would like to receive store emails. The original function is to stay intact, but additionally if the registrant checks the box, an automated email welcome message is to go to the registrant's email address upon completion of the checkout process (at the same time as the order received email goes to the store owner) The second modification is also on the registration page. An input field is required so the registrant can enter the name of a referrer. This should then appear with the registrant's (Customers)details in the View Customers section (after clicking 'edit' the name, address, email etc.. and then referror is also visible)