1) No
2) Your description sounds a bit harsh. If accurate, there sounds like a problem but are you sure that the noise is coming from the kompressor and not something else with the engine?
3) >>neither and sounds like something else?<< It sounds more like a roar to my ears. This is especially true when the car has been started from cold and the kompressor is on full-time during the warm up cycle. As others have said, your car will sound a lot like a tractor during this time period.