Change PHP form and MySQL Database on existing website

Hello, I need a few changes made to a website that already exists. 1 - Add a new field to the forms on the website to include the suburb (it currently takes Street and State) - this will include the update to the database to allow for the Suburb to be stored as well as updating some scripts that will utilise this field. The website generates emails based on the input which needs to display the new Suburb field. 2 - Alter the email script to allow for 2 different versions of the email as opposed to 1 all encompassing email, according to who the 'sender is' 3 - Perform some DBA work to clear out the current data (and back it all up) to allow for the streamlining of the database (some of the database enquiry tools no longer work as the DB is too large) 4 - Fix an issue with an unsubscribe script to make sure it works fully. Feel free to ask any further questions Thanks