'''Availability for room must be 0 or 1'''
The quantity for this room must be set to 1 in the Bedandbreakfast.eu system. Check wich Bedsandbreakfast.eu if you can raise the number to the number of rooms you actually have.
'''Can't set dates 0000-000-00 as available for room xxxx, conflicts with a booking for hotel id xxxx'''
Updates sent are rejected because of a conflicting booking which is already in the system. Most likely this is a due to a manual entry into Bedsanbreakfast.eu. To fix this remove the manual entry.