Add MORE SEARCH FILTERS on select boxes

Hello people, i need to add more search filters on select boxes. You can check the page that must be implemented here: [login to view URL] Each select boxes is referred to a product category. Actually sort filters are by name, price and availability. You can test them by applying sort by filter on top orange bar clicking on "nome"(name), "prezzo" (price) or "disponibilità" (availability). Now i need to add new sorting filters. Each new filter is specific for related category. I mean, for instance, if you need to select a memory, you should be also able to sort by manufacturer, memory size, frequency, module type. Same search method is already working on site categories page. Check memory category here: [login to view URL] On left side you are able to select more specific search filters like "produttori"(manufacturer), "tipologia memoria"(memory type), "frequenza"(frequency) and "dimensione memoria"(memory size). These are project requirements:. 1) Add on select boxes "More filters".By clicking it on select box will appear category related specific filters 2) Category related specific filters must be selectable on admin panel 3) Search must work on multiple search filters (for instance by manufacturer and by price at same time) 4) When a filter is applied , during product search, [login to view URL] script (already installed) must show filtering progress percentage as it happens when you click on a select box (rotating round orange div) 5) All page features must be kept working and intact Please note that my website is based on a fully customized version of Opencart but page [login to view URL] is built with custom php code. I WILL ASSIGN MY PROJECT ONLY TO SINGLE DEVELOPERS (NO TEAMS). DO NOT PLACE BIDS OUT OF BUDGET!!! PLEASE READ CAREFULLY ALL REQUESTS AND POST YOUR BID ONLY IF YOU ARE ABLE TO MANAGE AND COMPLETE THE PROJECT. Payment details : 100% milestone at project start. Milestone release will be completed ONLY when you will get my complete satisfaction.