If you see a school bus stopped, look out for the pop out STOP sign on it (think Morris Minor trafficator or whatever they were called). It means that traffic in both directions must stop. I got a filthy look when I passed by a bus in the opposite direction the first time I saw one of those
In my experience, other drivers are a lot less willing to give way (i.e. to pause and let you out of a junction into a queue), but are also a lot less likely to get wound up over nothing, so you can usually just pull out (of course assuming there is a safe gap) and no one minds. Not explained that well, but I mean that a gap which I might think is too small and therefore rude but still safe over here, would not normally be an issue over there.
Stuart
p.s. I suppose the downside is if you get this wrong, they'll probably shoot you.
p.p.s and of course you need to get used to (more) people passing both sides on multi-lane roads and speeds being very similar.