Modifications to Mosets Tree extension in Joomla

Are you familiar with the Mosets Tree extension? I need you to make 3 simple modifications to the system. 1. In the "Add Listings" page, Change the Category Selection box to a simple dropdown field. 2. In the "Spy Directory" page, add a feature to show listings posted each week / month. 3. Allow me to set how long i want "Featured Listings" to be displayed as "Featured". E.g., If i set it to "30", all featured listings should be displayed for 30 days, thereafter they will be downgraded to normal listings. Should be fairly simple to implement. Will award the project to an experienced programmer with good quality feedback. Please meet my budget!