Points I noted:
you have not set the MinimumFree Space setting for the ‘cache’ pool. This means if it fills up you will start getting ‘out of space errors’. This should be set to something like twice the size of the largest file you expect to write. Not sure if you encountered this at any point.
in a similar vein you should set the Minium Free Space setting for each User Share to set the condition for switching to another array drive. Probably not going to impact you until the drives start getting close to full.
there were lots of panic’s in the syslog that appear to be samba related. No idea of the cause.
you have quite a few .cfg files in the config/shares folder on the flash drive that relate to shares you no longer have. A good idea to remove superfluous ones to tidy up the diagnostics.
None of these, however, seem to explain all your symptoms so not sure what to suggest.