How do I stop my Galaxy S5 phone from waking in my pocket?
cause all sorts of bothers (skipping songs, taking pictures, etc)


Is the touch sensitive option enabled. As it will increase the touch sensitivity, your device will work abnormally for any touch like sensations (like that of keeping in your pocket).


  Is there some option in Android OS to stop the screen from waking up when it receives a notification? 


I guess not in our S5's stock firmware. So you either use external methods to stop it or turn off the touch sensitive and decrease the screen timeout.