Thanks a lot for your answers! Just some questions on your inputs, ...
for 1) I need a graphic card. There is no way to preconfigure it and replace the usb key?
for 2) I will recreate the RAID after installing. Do I've to cleanup before, or will it be possible to overwrite the whole config / data from the new installation?
for 3) any chance to get the drivers for the b.center (unsupported, I know)? Maxdata / Belinea does not exist anymore...