Custom website programming

Hello, We are in the process of creating several functions for our website. It is an auto website that customers and dealers can list their vehicle for a fee (like [login to view URL]). It will also have a business directory that will allow businesses to list their company at different membership levels, the top allowing them to advertise in different places on our website. I want them also to be able to post coupons. The last one is an interactive questions page that will allow users to ask questions and get answers interactively. I would like all of these to integrate with social media. We already have a design in place but we need someone to create all the programming above as well as a frontend, a membership login, and admin section. We need whoever we hire to continue to be able to create phone apps as well because when we complete the website we will need to have a mobile app with all the same functions. Thanks.