472873 three feature additions

I need to add the following features to a php script.. built with cakephp. Shouldnt be fairly simple. You can see the script here ...register if you need to [login to view URL] a. share with set amount of users and if they purchase you get it free. The share feature is already built. I just want to add the addition of 3 people buying from the share link and the users gets the deal free. * Some of deals won't have static prices; we can add a feature that brings down the price a dollar or so at a time when more people sign up. When the deal closes, everyone pays the last and lowest price. * produce a point system and offers cash-back credits. You accrue points for visiting the site, inviting new members, sharing and buying deals, and commenting and voting. You can see the first feature on livingsocial and the last two on homerun.