Again an inventory would be great for us internet sleuths to come up with theories. If he converted them to full auto, he probably realized he would run the risk of overheating barrels, therefore needing more guns.
As far as the luggage, he had 4 days to transport them up. He could have brought 1 at a time for 3 times a day and would have had all of them up there.
Fair enough. But that is a ton of pre-planning you are describing. Which again is weird for the lone gunman who just snaps one day.