I try to solve now one of the last problems.
When I switch off the monitor (HDMI Samsung TV) and switch it on again an hour later, the driver for the monitors audio is not present anymore, and no audio is playing. Its only if I switch off the TV for a long time. If I only switch it off for a minute it still works.
I tried to force quit coreaudiod and audiocomponentregister but no success. I need to restart the computer to get audio back. There must be a trick to tell the system to refresh the audio driver list.