Build an Online Store - Videogames, Consoles, Cellphones and other technics

Hello, we need online store - webshop. We sell videogames, consoles, gaming equipment, cellphones, and the other sorts of technical devices. This is our goods list: [login to view URL] Company name is Mobile and Game Center, we have our logo in png. Website sould be in Serbian Language, so we need to find a way for translation. We can do this if you create sometning like language files with strings for editing, we can accept your advice if you have better idea. Here is briefly what interests us. Clean, flat design - Responsive. Site needs to be lite, fluid, speedy. Avoid making separate mobile version if possible. We want to maximize UX, so everything must be user friendly. Admin panel should support drag and drop upload for images, and all other benefits of modern custom CMS (like Wordpress). We need full management of users, orders and other important stuff. We need stock management tools, like XLS product list upload. We don't need payment gateways (only PayPal would be ok). We want You to use the latest technology when developing, such as HTML5, CSS3 and others. Take into consideration the latest Google updates for SEO, integrate all the latest standards for SEO as well as rich snippet, structured data, mobile friendly, and others. We need all standard website pages like Contact, About Us, Terms of Use, etc. We need some kind of blog integrated into website. Site needs to support all kinds of browsing by category, by brand, by condition, by price range. We need a mega-menu, something like: [login to view URL] > we really like in terms of design, minimalism, general impression [login to view URL] > good megamenu, minimalism Menu structure: Menu should be categorized by platform: PS3, PS4, PSP / Vita, Xbox, Wii, PC, Skylanders, Akcija (special offers) and then platforms should be separated, for example: PS3 >>> GAMES (with picture) CONSOLES (with picture) EQUIPMENT (with picture) fps new gamepad sport used cables You can see example of menu structure on [login to view URL] Sidebar: 01. Major product categories (with a picture), you can see example on [login to view URL]: PS3 PS4 XBOX etc ... 02. Brands Rockstar Activision Sony Microsoft etc ... 03. Space for some of our banners IMPORTANT: - Smart search for products! - Social elements on products, such as, ratings, stars, comments (integration of Disqus) - Sorting items by several criterias: rating, the most sold, price low to high, by name - Variable items, that can be adjusted on the basis of which parameter is shown variations - shop view - grid and list Less important: It would be good to leave the possibility that somewhere in the sidebar is a feed from youtube clips that are automatically pulled for from yt channel. Each time you open the page that displays a random clip from the given categories (eg video games) ...