Cruman, totally agree. This makes me nuts. Not only they dont walk in a straight line but they walk in groups and slowly... I often get really annoyed and push my way in (would never do that but the simple "sorry" or "m'goy" doesnt work!).
For elevators, hk is a vertical city hence you spend a lot of time in elevators going up and down (just try and calculate how many floors you climb in an elevator per day here) so people dont want to loose too much time. But some, are just selfish and dont want to share elevators also.
I often press the open button (yes am a freak) when people try to come in. But half of the time, dont even get a thank.
In france you are supposed to hold the door to the next person coming, not slap it in his face, if you do that here, people will simply use you as a doorman, no thanks no nothng, they will walk through... Did that one or two times when I arrive, dont do it any more. The hardest is to get rid of those bad habits when coming back to France!