"how many A340-600 has Cathay ordered and on which routes will they be deployed?
Do they have also some A340-500 on order?"
They actually havn't ordered any. They are leasing 3 from ILFC for, IIRC, seven years. They have no -500s either on lease or order.
"Both numbers are far lower than the Airbus number of 380."
Both manufacturers tend to inflate their seating numbers to make the aircraft more capable than what they really are. However, with the case of the A346, Airbus went above and beyond. If you look at the comparisons between the "standard" seating of the -300 compared to the -600, virtually no seats were added to either first or business class - all the extra capacity was assigned to the more densely configured economy section. This makes the "typical" 3-class seating given by Airbus highly inflated. In typical airline configurations, expect @ 315-330.
Honor the warriors, not the war.