Add extra functionality to existing Drupal-based site

I have a simple Drupal based website that needs three improvements and some maintenance. The first task is to add a new tab which allows the user to make some calculations and feeds them some data, in the form of a chart. The data in the chart helps them in making selections for the calculations. The tab must show up in the main menu. The second task is to amend the content administrator’s panel so that they can upload data to create the chart for this second tab. The data for the rest of the calculations is already available in the site. Data upload should allow either individual records to be amended and mass data upload using a table that accepts csv files. The third task is to add a ‘clear’ or ‘reset’ button on the two pages that allow users to make calculations. This clear button will erase the user’s previous selections and allow them to enter new choices. The fourth and final task – maintenance - is to ensure that the site is upgraded to use the latest Drupal core and all modules are up to date. This project is suitable for a freelancer with experience in Drupal, php, css and mysql. For details, budget and timing see attached file.