Change "no shipping" options

We are using Marketpress to sell CLASSES, so there is no shipping requirement. I have changed the store settings to "no shipping," but would like to change the displayed text on the screen that STILL appears that says "shipping options" (followed by Name & Special instructions).

I would like the "Special Instructions" to say "How did you hear about us." If that's not possible, is it possible to have a customer visit a FORM before completing check-out where we can capture that information?