Thought I'd through some comment in also...

Speed limits
Yes, as Geoff say generally 50km/hr on regular "busy" streets in the city with the traffic flowing faster than that. I would cautiously say that you can drive up to 10km/hr over (except in 30km/hr zones) without getting a ticket.
Watch out for some streets along parks, though construction areas, and some lanes where the speed limit drops to 30km/hr.

Pedestrians
Talking to a coworker in Edmonton, they raised fines for crosswalk infractions due to a number of pedestrian accidents. My buddy received a $700 ticket (yup, seven hundred) for not yielding to a pedestrian that was just about to enter a crosswalk. I was driving behind him and watched it occur. The pedestrian wasn't even at the curb yet but he got the ticket. I stopped for the pedestrian though

Realistically, whenever the pedestrian has a green light to cross or wants to cross in an identified crosswalk, you should be yeilding to them. In an uncontrolled intersection, middle of the street, etc. pedestrians usually exercise caution by yielding to the car. I don't think the average pedestrian expects you to stop along a busy street to allow them to cross (crosswalk & pedestrian controlled light excluded).
What's the law? I'm not sure. But in the end, who wants to end up having to deal with hitting a pedestrian with their car? Just be cautious.

Four Way Stop
Yes, first person there gets the right of way unless of course, pedestrians muck up the order and everyone gets confused.

Miscellaneous
I find that there's way less driving courtesy in North America than in the UK (eg. Slower traffic doesn't yield to the right lane for faster traffic).
There's no speed photo radar anymore in BC but there are red light cameras.
Seatbelts are mandatory.