It's summer time, there's going to be road construction of some sort on most any route you take I suspect.
I would prefer the southern route to Rochester if only for the fewer tolls and for avoiding the greater Chicago area (though the northern route does avoid most of the worst of it, of course). The NY Thruway is not all that easy to avoid if you want to stay on limited access highways, and always seems to me to be rather expensive, whether or not it actually is when compared with other states on a cost per mile basis.
Driving in Canada is not much different from in the US. Road signs in Quebec are in French, but it's not too hard to decode what's going on even if you don't speak French. Speed limits, clearances, and distances are in metric units. The highways are nice, and city driving is much like city driving in any city. For the most part, the signage is similar to US signage—a red octagon is a stop sign, etc.
Do be aware of the various laws related to border formalities and what can and cannot be taken into Canada. You definitely need a passport or enhanced driver's license, and if you carry guns you definitely need to make sure you comply with the applicable laws and have the proper paperwork. Pets I believe need to have certain paperwork regarding vaccinations etc. as well. I'm not sure if it's technically required anymore, or perhaps it's only needed in some provinces, but it would be a good idea to get a Canada (vehicle) insurance card from your insurance agent to avoid the possibility of difficulties (a "yellow card"). US insurance policies typically cover travel to Canada, so obtaining the card is just a matter of asking for one and perhaps waiting a week or so for it to be mailed.
