Create a Wordpress Template

Hi I want to move our website to php / wordpress. Its online and has a lot of information, but its on python / django and not mobile friendly. We want a responsive new website. We would like to keep the existing menus and sub menus. The address is [login to view URL] and we would like to use the backend / database on the new version. There would only be minor design changes. I would like to know the cost and timeframe for this project. Thanks Rubens