Re: Working in Canada
Carnet filing may be needed, listing all equipment being brought in (so they can make sure you take it back home). This has been discussed on PSW forums before (and maybe here). The carnet is a form of bonding to help insure that that all items imported are exported (or duties and customs fees collected if the items remain in a foreign country or if the carnet expires).
From a personnel standpoint, you will need to make sure you are eligible for admittance to Canada and determine whether or not you will need a work permit (likely). Generally your client should secure the work permits. Not sure how long that takes, but the sooner the process is begun the sooner you'll be certain. It's been a decade or more since I've been to Canada so others will have better and more recent information.
One thing that will almost certainly keep you from entering Canada: felony criminal charges in your home country, or being charged with a crime that is a misdemeanor in your country but a felony in Canada (DUI is *the* prime example). It doesn't matter if the charges were dismissed, that you completed diversion or that that a conviction was expunged... you'll have to apply for "criminal rehabilitation for entry to Canada" (IIRC that's how they word it). Canadian immigration/customs has detailed information on their website, and an email or phone call will be probably be needed if you have reason to be filling out those forms. They have different requirements based on length of stay and presumably purpose of visit. If these circumstances apply to anyone desiring to enter Canada it is best to begin the process early. Several years ago I was in catering with some tour drivers - one was telling about another driver who had an 8 year old DUI conviction in the USA, who was denied entry to Canada. His employer had to find a Canadian driver and arrange for deportation of the first guy back to the USA (I guess you can't just walk back across the line).
You'll need your U.S. passport or passport card.
Canada is a beautiful country with lots of smart and generally friendly people. If you're prepared you'll have a good time.