No ruffled feathers! sorry if it came across that way!
The "cross check" varies with airline, i work long haul BA now but before i was with TCX and they never used that phrase as their door arm/disarming procedure is different . Each process was said out to the other crew member who would reply with "confirmed" or "stop" before each action so it was a case of pointing at the arming lever before moving it.
My only reasoning with BA is with the double checking of everything safety wise just like in the flight deck as they still read from a check list to make sure all is done right. You'd think that when landing, having the gear down would be a good idea but they still verbally double check!!
As for the DC-10 door, as i said all aircraft are different but what has prob happened there is that when the aircraft pulls onto stand the dispatcher knocks on the door, he should stand back and there should be a delay of 10 secs before the door is opened.
On most large aircraft the doors are power operated when the door is armed to aid with quick door opening in an emergancy as the doors are bloody heavy! The "power assist" as its called, is in the form of a compressed spring or compressed nitrogen acuator.
As the dispatcher knocked on the door he's stood by it to help the crew member open it as with the door disarmed there is no assistance to move it. (except the likes of the 767 with the door goes up and it can be moved electrically)
The door has still been left in the armed position causing the power assist to activate throw the door open hitting the dispatcher. The doors open at some speed when the power assist is activated and it is known that some crew members have been catapolted out by not letting go of the door causing death or serious injury as they fall 12 odd ft or more.
As i said before all aircraft are different and having never flown on a DC-10 i'm not sure the exact door mode but using knowledge i know now and also gained as i studied aircraft engeineering for an apprenticeship pre 9/11 when the course was disbandoned due to the events on that day.
Hope this helps an feel free to ask any more questions that you may want answered.
kempus