UPDATE:
I got it to fly. And crash.
Anyone good at reading logs that might explain what went wrong? (See new topic here in that case).
http://discuss.ardupilot.org/t/help-with-reading-log-files-from-missionplanner/9517
And thank you for all the help Netphreak, seems like the RC calibration was in the fault. Redid it two times AND made new ESC-calibrations afterwards and after the second time the speed was ok.