No data required. In fact, my "real" phone is an Android and the iphones I've used during development never had a plan. I did find out, however, to add a new (to me) phone to itunes and set it up you need a SIM card. I just pulled the card from my Android and away I went. After setup I yanked the card and everything worked perfectly.
Good luck at the Sandblast! Post a pic if you end up using the app.