customized second level specials page

we have a zen cart shopping system. On the Step 2 of 3 payment information checkout process, i would like to make a comprehensive specials/discount on products offer to customers where centain level of discount on products will show depending on how much money the customer has spent. eg, if customer spends between $100 and $200, on this step, just above the continue checkout button it should show CONGRATULATIONS, you are eligible for additional discounts and special offers, click here. with a link to show all the items (in that spend category) they can receive a percentage discount off or a special price on products that admin selects. admin should be able to create unlimited spend categorys, eg 100-200, 200-500,500-1000, etc then for each category, admin selects products on that category with a percentage discount or special price per product. the user can enter qty of the products they would like to add to their order. so there will be an admin section and the user section on this project. Also, these special priced products that user has ordered must be identified to our administrators when the order is emailed to us like, "***" infront of the special price products, so our admins know which products were given away as a special... the special price must be obviously calculated and shown to user. for additional info, message us.