The expansion of “Canada” into the NW Territory was actually one of the most major reasons for rebellion and the creator of the sentiment of the end of salutary neglect far more than any taxes. With French Canada, the colonials would remain loyal to the Crown in face of any invaders, even if protests would get a bit tense in face of taxes. If there is a rebellion, it is much smaller and isolated in New England.
Possibly. On the other hand, if the French have been pushed beyond the Great Lakes then the colonists may feel reasonably secure enough to challenge the British.
The question is how much of Canada is French here. Just Lower Canada? Is Upper Canada included? What about New Brunswick?
Assuming New Brunswick and Nova Scotia are British (ergo all the disputed lands are British here) and the Ohio country is British, I think there'd be an open issue of the Ohio Country during the war. The French/Canadiens will likely be trying to retake part or all of the place during the war, much to the Americans' chagrin.