Crear una tienda virtual

We need a Shopify expert to build and deploy our Shopify B2B ecommerce website, for our clients to login and place their orders by themselves, giving the option to pay immediately by credit card or forward the order to their salesperson’s email for further processing. We require help with the design of the Shopify site with the follwoing features: 1. Login with username and password for clients (only previously approved and logged in clients can see prices). 2. To upload all products at the same time via template or excel file including SKU, title, description, image, call to action button, etc. 3. Fully compatible with mobile devices like smartphones and tablets. 4. Fully customizable by ourselves (banners, texts, images, products, categories, sub-categories, etc.). Thanks.