As for the debugging question:
Debugging hard drive issues are usually a problem because when the error message is generated the log no longer gets written to the disk.
The solution I normally use is to forward a copy of the logs over the network to a external system, so that after the crash I can see the error message (and hopefully get useful debugging information)
While incomplete, the beginning of talking about logging is here:
In your case you would need to log dom0, which has not gotten addressed yet in the document, but it appears rsyslog is installed in dom0, so presumably you could just add the file to /etc/rsyslog.d/ on dom0 and it should get to the logging qube.
Unfortunately the part on forwarding the logs to a external system are not complete yet