Build an Online Store 2

Hello, we are running an online store and we wish to revamp the checkout page as well as create a new admin panel. What we require is the following: 1) One checkout page on a separate domain integrated with existing web stores. The checkout page needs to have a strong php code and should not be open to SQL injections. Should be able validate Visa, Master Card and Routing Number of checking account. 2) "My Account" page for customer: Customer should be able to check on the status of his order. 2) Admin Panel, backend: a) Ability to check on order, modify orders and download it in CSV format. b) Auto Emails