The motor city and Canada i would love to hear about what it was like under the US for the Canadians, did they see the US as protectors or conquerors, where their Militia groups that fought against the invaders, how did the french speaking parts take it? Did the French speaker rise up against the English speakers carving out kingdoms? Canada be it Montreal, Toronto, Vancouver, Edmonton/Calgary...etc would be very interesting. Ed/Cal could be an interesting DLC where the two cities have been waring with each other for hundreds of years, since they have oil they might have been able to even use machines at these in the begining. Vancouver is close to the border of the us and close enough to alaska to have actually seen some chinese invasion forces and has a large chinese population too.
I want more Chinese stuff in the next game, i loved those parts in FO3 and Cape Look out.
1. Check out the Vault wiki, and it'll give you some background to the pre-war Fallout Universe, and help you learn a lot about what's what before, and how it all came to be.
2. Canada did not see the US as a protector, they were fighting to keep Americans out. When the war with China started, they refused to allow US troops and supplies, to come across Canada in anyway, including their airspace. That's when the annexation for Canada, started to come about, because the Canadians gradually gave in, and the US could do whatever they liked. The US started cutting down their trees for lumber, and taking all the resources they could from Canada, as they began to annex it, under their own control. So no, the Canadians didn't see the US as protectors, but as invaders. Plus, there were plenty of riots by Canadian citizens, against the US's invasion, and an attempt to sabotage the Alaskan pipeline. So you can bet there were some form or Canadian militant resistance. If you play Fallout 1 as well, there's a little news reel, that shows two Power Armored American soldiers, executing what's probably a Canadian Resistance fighter in Combat Armor.
3. There wouldn't be any oil, or enough of it at all anymore, that's the whole point of Alaska and the pipeline. It was the last place on Earth as far as we know, to have any reasonable amount of oil, and that's why China invaded it. Also, they likely didn't invade all of Alaska, only where it mattered. Sort of like the Japanese in WW2. They didn't invade all of China, only the parts that mattered to them, which was where the resources were. The entire country wasn't invaded, just parts of it. Alaska would be the same way, with what was called the Anchorage Front Line.