Default [Q] Creating a custom Android telephony application

I am a novice Java developer and need to create a custom Android telephony application with the following functionality

launches automatically when device starts , boots
launches in kiosk mode, no notifications, or access to other applications!
has a single 'call' button which places a phone call to a hardwired phone number.
has the ability to communicate 1 way simple data to external device(think arduino) via bluetooth. i.e. when call received signal to arduino to flash lights, etc
optional display for either hardcoded message or number received.

Should I make use of a single Activity class?
What other classes should I create or make use of?

Are there any Android projects on Github or elsewhere that have parts of this functionality I might study and learn from?

Any other architecture tips or suggestions?