The FAST card wont help you much if the bridge is backed up. Canadian customs is usually pretty decent and polite. Coming back to the states is another problem. BE SURE YOU HAVE YOUR PAPERS AND MANIFESTS IN ORDER!. These people can be real pricks at times and they have no sense of humor. Dont make small talk with them and dont joke around. Just yes sir and no sir. If they sense you are nervous or uneasy about something, you will get pulled around to secondary inspection and waste a bunch of time. You might even get sent to immigration if they feel like it. They also do random inspections and sometimes they are looking for something in particular because of tips etc.
A few months ago I was crossing the Champlain border into Canada. I've gone into Canada 15 times over the last year and everytime I get asked about my smile on my face. I never tell them the truth, but when I'm looking at a woman candian border cop I think to myself I wonder if she shaves or not.