Another possibly dumb question: I’d like to control the music playback on my smartphone (which should be doable via bluetooth as my car stereo does it every time). Like with the music player when you wipe to the right. So I can use my watch as a remote control when I ride my motorcycle. Can it be done with built in stuff? Or is there an app for it? Sorry, my knowledge about that android stuff is just not existant - yet 
I don’t think it’s possible at the moment. The Bluetooth stack in the watch is not a complete stack and that’s why using it for other companion type operations is also not possible (voice calls from your phone to the watch for example).
I must admit I am chuckling to myself imagining you driving your motorcycle and trying to change audio tracks whilst wearing gloves 
I don’t know if I understand your question correctly but you can try:
https://play.google.com/store/apps/details?id=com.preiss.swapps.link&hl=de
It is sometimes a little bit buggy but sometimes it works fine. And you can control the music-player on your smartphone and many more.
@michael_fischer yep. Good app but tends to eat your battery…
Also not sure if it would achieve what Haggis is asking for while riding a bike…
Thanks for the input, I guess I will go for this one then…
http://www.amazon.de/gp/aw/d/B00RM75NL0/ref=mp_s_a_1_1?qid=1463867833&sr=8-1&pi=SY200_QL40&keywords=bluetooth+fernbedienung+iphone&dpPl=1&dpID=415d5eu%2B%2BML&ref=plSrch