Develop Firefox extension

General: Develop a Firefox extension compatible with version 8 or newer that displays content with the opening of a new tab by the user (without a button just by clicking the + sign) and shows a photo and some text returned via ajax as a json object from a current working server. The extension needs to have an option button where the user can choose to use this new tab or not and a placeholder of more options to be stores locally for the future. The extension also needs to grab a js file from a website (different address) and add it to a working webpage to enhance the user experience. Code needs to be clean, readable and each function/ page clearly explained. Code submitted CANNOT be minified and has to allow further future development. MUST HAVE prior Firefox development experience and examples. Selected developer will get url for current working extension in chrome to better understand layout.