Unfortunately there are no examples using the XDK with Bluetooth applications. However, the following guide might be of your interest: https://software.intel.com/en-us/blogs/2015/05/19/communicate-to-arduino-code-with-your-android-phone-by-bluetooth-seria…
Regarding you question about how to program Android apps, I think you should use the tool that you feel more comfortable with. Since this is your first time programming Android apps, you might want to refer to the Android Developers site: Develop Apps | Android Developers.
Thanks a lot DiegoV_Intel