Customize image upload system for Ecommerce Wordpress marketplace - PHP and Javascript

Multiple image gallery function Base platform: Wordpress 4.0 Easy Digital Downloads Easy Digital Download - Front End Submissions Extension Marketify Theme General overview: Starting with the aforementioned platform, create a custom image upload manager. Link these images and all collected data seamlessly into WP Easy Digital Downloads by including the collected images in digital product listings. Specific background: Modifying Image Upload Functionality- We need vendors who are accessing our site on a low permissions level to be able to attach more than one image to their digital product. We do not want the user to see the default [login to view URL] media manager. But instead, we would like them to be prompted with a custom empty window devoid of all prior media. We would like them to be able to add 5-10 images within this window. The upper leftmost image should contain a box around it and a label of “Featured Image”. The user must be able to click and drag the order of the images to organize the order they will be displayed along with the product. The image that is dragged into the upper left most box, must serve as the products featured image. Modifying Easy Digital Downloads and Front End Submissions to Store and Display Images- The image data collected must be stored with each digital product. The featured image will serve as the thumbnail for the product on the storefront. The other images must appear as thumbnails when viewing the product details page. A;so, the Front End Submissions, Product Submission form must be modified so that after the vendor uploads the images, they immediately see the thumbnails on the product creation page. The themes and PHP must all be updated accordingly to achieve this. Work practices- You must take care to avoid all venerable commands and use the most secure practices possible. Avoid hard cored URLs and variables. You must document all changed files for code review by our internal staff. Build this so it plugs in seamlessly to the current Front End Submissions system. Preferably having it install as an API plugin. You must demonstrate progress every 5 days at a minimum. You will need to set up your own copy of WP with the base platform and demonstrate the work on your own server. Quote for this work must be all inclusive with no unexpected or additional charges.