Store to sale documents to download

Hello There, I need an experience and serious coder to make me a online store. You will use an open source, design has to be simple, nothing fancy. * Landing page displays categories. Clicking on a category displays products and sub-categories. Aask me to choose the template first. * The stock of the store is populated with web forms filled on another website, comming from Gravity form, no manual entries. * About 4 categories of products, with sub-categories, and ability to add more. * Price to be set per sub-category. * Each new form submission goes directly in the correct sub-category, and becomes another product available. * Dispaching in the sub-categories are set in regards with answers on the web form. For exemple, if customer answers "blue" on the webform, the document to download will be in sub-category A. If he answers "chicken" on the webform, the document to download will be in sub-category B. If he aswers both "blue" and "chicken", the document to download will be in sub-category C. IT IS CRuCIAL THAT THE DISPACHING CAN BE MADE IN REGARDS WITH THE WEBFORM ANSWERS. * Each new entry create datas, that can be downloaded as excell or csv document. * The product SHORT description displays some felds of the webform, the product LONG desription dispalys all fields, EXCEPT name surname, street, phone and email. Everything else, including town and zip code is diplayed. * Shopers much fill a form, answer the questions and receive manual aprovement from admin (me) before thay can shop. After I accept them, shopers will have an account on the store. * Shoper must have the possibilty to set an email alert when a new product comes. Email contains a link to the product. * Payment by paypal. Once the payment is done, the shopper can choose to download the document, as excell or csv,and downloads. I will install the open source on the url, and will give you admin acess. 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.