Hello Mark, and welcome to WebmasterWorld.
I don't know of any one website that has all of the things you are looking for, but a good source of info when I was starting out was Export Development Canada [edc-see.ca]. I think the rules and laws may be very different depending on if you are selling a service or hard goods. A couple of things to keep in mind though when selling to our friends to the south.
1) Price your goods, or services in USD. Trying to explain to potential customers that the Canadian dollar is undervalued and makes items cheaper really doesn't work. This thread speaks well to that [webmasterworld.com]. You will need to establish a U.S merchant account to accept credit cards, and open a U.S based bank account. Be prepared to jump through hoops as far as the merchant account goes, but feel free to stickymail me, and I will point you to some good resources.
2)If you are selling hard goods into the U.S, get your self a good logistics company to walk you through the parts of the NAFTA agreement that will apply to your situation. I found trying to deal with this cryptic trade deal, and all of the reams of paperwork that accompanied it to be incredibly frustrating, so save yourself the hassle. Again, feel free to stickymail for specific resources. A huge challenge when shipping south is the acual delivery part of things. A good logistics company will be able to help you with that as well.
I am really surprised at the lack of Canadian retailers serving the U.S market, as we have such a big advantage in being able to buy in Canadian funds, and sell in greenbacks. Right now, 1 USD fetch's more than $1.60 CAD:)