What would be the best way to implement a new set of input elements to the checkout? Is there an add-on out there to address this (I have looked but to no avail)?

In essence during a stage of the checkout I'm looking to add a few text boxes/checkboxes asking questions based on the customer's experience, and if possible for this data to be added to the email that the client receives when an order is complete.

Does anybody have any ideas?