Our team had a lot of success getting the Bluetooth up and running using Tutorials 4 and 5 provided on this site, but we struggled with two-way communication (we could send information to the Arduino from the Android app, but we had trouble getting information back from the Arduino into the app). We've found this video to be very helpful, and we thought other teams would find it useful as well: https://youtu.be/JQ3tDhpmSFE