Are there territories where people tend to be from one nation over others, the way those from Quebec are usually French?
Not really. You've hit the main one- the French of Quebec. This is because after the Americain revolution, the English Loyalists who were loyal to Britain where forced to leave America for Canada. The Loyalists refused to be governed with the French speaking Canadiens. The Governor of the time realised that the French would never give up their langauge or customs, so Upper and Lower Canada were created. These areas are now known as Ontario and Quebec.
In British Columbia, there are many Asian people because of the building of the Canadian Pacific Railway. Many workers from China came to work on the railway and they settled in Canada after the railroad was complete. I believe there were many Irish who also worked on the railway, mainly seattling in the Altantic provinces.
How do you believe Canadian schools for magic would be different from Hogwarts?
Well, there is population. The school would probably have a smaller amount of students simply because Canada's population is much smaller than Britain's. On the other hand, Canada is a much larger country. There would probably be more space for a wizarding school or community to work with.
Wow, that was more historical than I intended... I must have actually learned something in Socials....