Hi Natascha and thank you Lukas for the very good input
Our current SDK is not supported on kernel 4.4.0 but we already have made an internal fix for this, which i can share to you. But just notice that this is non-released/unofficial sw. We believe the patch for 14.04.04 also work on 14.04.05 but have not confirmed it - hope you can help confirming it.
For your second question unfortunately we currently to not have other material than the HID 3.0 document available. But i suggest you to try the demo client included in the Linux SDK for understanding the signalling flow etc, as the principle is similar. Functions such as headset battery status is not exposed/available when working 'around' our SDK.
Hope i clarified your queries.