How can i disable iTunes autoplay when bluetooth device is connected?
This is a common issue on Mac. Here is the tutorials that works fine on my rMBP with OSX 10.11:

1) Open a Terminal Window 

2) Rename iTunes.app to MyiTunes.app 

3) Create a DoNothing.app using the AppleScript Editor 

4) Copy the DoNothing.app to the Applications folder

5) Connect a bluetooth device to get the "Where is iTunes?" window prompt and Select DoNothing.app as what to auto-launch instead of iTunes 6) Closing thoughts about updates etc.

Resource: https://discussions.apple.com/message/25425864#message25425864