WHY?
Canada is an oil exporting nation. More supply, they'll make less money.
Unlikely, as the amount that might come out of ANWR would not seriously impact the world price of oil.
Traditionally Canada has opposed development of oil in ANWR because of the western arctic caribou herds that roam between it and Canada. These are some of the last mega herds of grazing animals and an important part of life for the Inuit. That's not to say that I agree - I believe any disruption from development in the area will be minimal. Basically the Canadian government's position is the same as that of many Americans. Possibly a hypocritical one because we have big diamond projects going on up there, although with strict environmental regulations.