Prestoshop - ZIP code selective sellers

We are developing a shop with Prestashop 1.6.0.14 with Agile Multiseller Module. Purpose of the project is to give ability to customer to choose and display sellers who opted in to serve certain ZIP codes in the US: 1) Add to database and seller Business Info tab a new field for entering the served zip codes in the US (one field with zip codes entered with commas is accepted e.g. 75063, 76012, 65666; better suggestions welcome) by Seller 2) Add a block to frontend template which will add a zip code entry box to the main page along with an admin managed backgound picture (see attachment) 3) When user opens the home page and enters the ZIP code 3a) Query will check ZIP codes with sellers. The next page will display the categories as rows (in sort order), seller as columns, and products in the intersecting cells (see attachment). This view requires some design. 3b) If no ZIP codes are matched, the user will be sent to Google Forms 4) When customer changes the quantity, the item will be automatically updated in the cart (ajax, but no add to cart button). If decreased, will also decrease in cart. Changes to the code should be documented. 1) all changed files should be listed in this project in to Word document. i) modified files and DB entries ii) description of changes made 2) changes in code should be commented out // BEGIN MEALZE //END MEALZE 3) codes should not be removed, but commented out // REMOVED MEALZE This is a small part of our project. Freelancer who successfully completes this will get more customization as business.