Android Question Bluetooth communication protocol

Hi,
for my outdoor app I need some external pushbuttons.
I believe the bluetooth headset adapters below will give me this functionality.

http://www.pearl.de/a-HZ2037-4041.shtml
http://www.sonymobile.com/de/products/accessories/stereo-bluetooth-headset-sbh20

It's easy to find and connect the device with BluetoothAdmin + Serial.
They even start communication be sending "AT+BRSF=25" to my app.

Is there an expert in our community who knows the protocol and can help me to go on ?

Another approach may be emulate an audio app like jukebox, because they work perfectly with these devices.
But the B4A MediaPlayer don't fit.

Thanks
Rainer