OP, I have a cabin in Ontario on a border lake so I cross the border quite frequently. Be sure not to bring any chicken products with you including eggs unless they are all ready cooked. They also will give you grief if it seems you didn't clean your boat before crossing. One can bring one case of beer or one liter of booze per person in the vehicle. I'm not sure about tobacco but there are similar limits I have heard. They also wont let you bring any raw vegetables across such as potatoes unless they are commercially packaged.
The normal questions I get asked are,
Where are you heading?
When are you coming out?
How much alcohol?
Any mace, pepper spray, stun guns, or pistols? All of which are prohibited.
Are you leaving anything in Canada?
When was the last time you were here?
Where is everyone in the vehicle from?
Hope this helps.