I am using vs 1.3.9. I am a .Net developer and comfortable using databases, however I am new at PHP and Zen cart.

I would like to add a form to my downloadable product. The form will allow a user to enter information that will be committed to the database. After the user has paid, the link provided for the download will query the database with the users info and generate a pdf document for them to download.

1. What addons should I include?
2. How do I customize my product page to display the form? Or include a link to the form?
2. How do I keep track of the user during the filling of the form and ensure I populate the Customer's correct details at the PDF download? Do I use sessions, cookies, customerID in db?

Your help will be greatly appreciated.