Crossing the line...

Last week at school we were in class with a recruiter. And when the subject of going into Canada came up, he said in an animated fashion, " Boy! you had better have your ducks in a row!'. I pressed him to elaborate, but all he could come up with was having a passport and having your rig/logs up to snuff. All three i view as being routine and expected. So is there anything else to know about going North? Crossing the border as well as driving in Canada... They don't drive on the left side of the road do they? What about speed limits? I imagine everything's metric... What about weight limits, H.O.S, HAZMAT, or anything else peculiar to canuck-land? And what's a Canuck anyway? I'm particularly interested because my location dictates a high probability of going there. As always, any and all replies are greatly apreciated.

P.S. During the critique of my CDL road-test, my examiner said, "...During that turn off E onto OO, you didn't actually hit the curb with your trailer tires, but you got so close it made the trailer wiggle a little." (he took no points.)