Inventory / Order management Platform - Ebay, Amazon, Opencart & Zencart

Basically I am looking to create a website like [login to view URL] / [login to view URL] I need the following: 1) Website which people can sign up for order/inventory management (Accepting credit cards - HTTPS & PCI DSS Compliant) - Needs to be managed through the master admin indicated below 2) Website which these clients (+Master admin) can sign into 3) Master admin should be able to: - Add/Remove/Edit Customers & Information - See what customers are doing in their logins etc - Only give some customers access to certain things e.g. 1 ebay account - Access these customers account through a master password - Have a 'ticket' section where customers can ask me technical questions and i can answer etc (They receive replies through their admin side (not emails!)) - Flag up if a customer has not paid 4) Customer Admin should be able to: - Import products from ebay/amazon/webstore (edit etc) - Upload new products etc - Variations of a product - multiple ebay listings etc per product - All orders in one place (ship / refund / email customers) - Settings (set up webstore) Other work to be carried out if this goes to plan: - Computer program (POS - links up with this) - shippment link with royal mail, yodel etc (print postage labels for the product weight) - Magento, oscommerce, etc link - Regular updates etc