Have you considered a PHP Framework? PHP should be a fast learning curve because of your JavaScript knowledge.
As far as your “codebase” is concerned I can recommend [CodeIgniter] (http://www.codeigniter.com/) because it is simple and fast as storing and retrieving your data. Your JavaScript can then be used to manipulate the retrieved data both server-side and in the browser.
There are numerous other PHP Frameworks which may also suit your requirements, some simple whereas others can be complex.