Customize existing open source ecommerce

Customize an existing prestashop, or any open source cart template. The online store sells excel documents; I manually add them in the stock (category and sub categories). What you must customize : * The product descriptions displays all fields from the excel document that I upload EXCEPT a few of them (I will tell you which ones), they are the same for all categories. * Shoppers much be manually approved by admin before opening an account and buying. * Payment by paypal. Once the payment is done, the shopper can download the excel document (he receives it in his email, or he is redirected to the download page, whatever is cheaper). * Shopper has an account, on which he can view his buying, re-download. I will install the open source on the url, and will give you admin acess. That should be done in 2 days, so don’t ask too much. Payment by millestone, only when when all functions are working. NO PAYMENT BEFORE THE FULL JOB IS COMPLETED. NO PAYMENT A SINGLE HOUR OUT OF DEADLINE.