Need help with Pro Sites

I need help changing the signup process as part of pro sites. I need to split the signup process into 3 separate pages which follow on from each other.

The first page should stay as it is currently configured. On the second page users is directed too needs to have a slightly different URL so we can track user interaction. And then we would like to create a third "Thank You" page.

Our main goal is to track user information. We need to be able to track users who begin the signup process but don't continue. We need to be able to track users who have completed registration but have not verified their account. Is there any method or workaround? How can we track those users info?