Customize existing Zen Cart eCommerce site

Customize existing Zen Cart eCommerce site to operate solely for Sales Representatives to place client orders. The existing Zen Cart site is roughly formatted, and the layout established. Admin is set up. Site is populated with products, specs and prices. In it's present form, it is essentially complete as a 'stand-alone' eCommerce site. However, we want this site to operate SOLELY as a tool for Sales Reps to place their client orders. Access to the site is configured in admin to require registration or log-in as the opening page. We would like to customize this page in the following way: The 'choose password' field of the existing registration/log-in page is to be modified to be 'Request Password'. Activating this link would save the Sales Representatives registration information, and send a message to admin requesting the issuance of a password. This password would be issued by admin, automatically entered into the site database, and emailed to the sales rep allowing them to log-in at the registration/log-in page on their next visit. Once logged in the Sales Representative would be taken to a second data entry screen - similar to the opening registration screen - with 'Required fields' for: *Purchase Order number *Shipping Name *Shipping Address *Telephone Number *eMail address *Contact Name *Billing Name (If Different) *Billing Address (If Different) Billing Name and Address linked to existing, configured, Paypal Website Payments Pro payment module. Shipping Name and Address linked to UPS site to generate printable mailing labels. Once all required fields are satisfied - the Sales Rep would be taken to the Home page of the site to generate the order. The rest of the site would operate 'As Is'. At 'checkout', Credit Card information for the Buyer would be entered into the payment module which is configured to 'Authorize' payment only. Admin is already configured to send out emails to the Buyer, Admin etc. - it needs to be configured to also send an email to the originating Sales Rep who places the order.