I didn't interview at the Indy campus so I'm not sure if I can be of much help here.. But in terms of traffic, as long as you get out before rush hour the traffic is really never too bad on the way to the airport so I'd say 20 minutes is pretty accurate.Congratulations on your acceptance!
What time does the interview end? In the email the final encounter seems to be the information session at 12PM. Is there anything else after that and when does it end? Google Maps says that the Indianapolis campus is 20 mins from the Indianapolis Intl airport. Do you know how bad the traffic is on that route? Thanks!