Drupal - Translating languages functionality

Hello, So we have a drupal based site, and we need to translate our content: Specification of work: Drupal Version: 7.26 "The language translations pop-up would appear on the home page when someone enters the site with options for languages and the whole website would be changed to that language. If something is not translated into the specific language it would be displayed in English. Once someone has made the selection, if they want to change it, they can use the language buttons at the top right hand corner. The language which is currently selected should be bold and underlined. - In the backend we should be able to turn on and off the pop up. If we feel that people are not liking it we ourselves should be able to turn it off. If a user is using Arabic, for example, and they click on an article which has not been translated, there will be a text box indicating that "This particular text is not currently available in your preferred language". We also need a feature so if someone is browsing the site in English but wants to read a specific article in Arabic they are able to see the translation for that article only (language selection option just above the article), without changing the whole menu into that language. It would only effect the specified article." Please do not bid if you are outsourcing work and not a developer yourself.