Paypal IPN (Digital Goods) - Need some options Add/Remove

This a small project about Paypal IPN integration for digital goods. I downloaded Paypal IPN script from [login to view URL] and it is working fine for me. But I want to add and remove some options in/from the script. I am looking for the following items to be included in the script: 1) Remove the Subscriber code and keep only Digital goods option. 2) Product selection option: Concept: - I have a range of products on my website with product codes. I want the customer to be able to select the product and click on the 'buy' button then a Paypal payment box should open in popup window (see example below link) and on completing payment provide the product download link to customer. [login to view URL] 3) After payment completion a confirmation email should be to the customer. (I will provide you an email format) I attached my Paypal IPN files. I am using Wampserver 2.0. You will need Paypal Sandbox details to run this file.