yes.
Canadians can only travel with the country of Canada without a valid passport. A valid passport or a valid permanent resident card are the two acceptable forms of documentation to re-enter Canada without issue.
when does a us citizen need a passport to drive to Canada
yes
yes because you live there but you need it to go to Canada
Even Infants can enter the US with their US passport. So there is really no age limit to one who wants to enter as long as they have appropriate documents.
6 months
yes, all entry into Canada is required to have a passport, you'll need it to re-enter the US anyways.
No.
Everybody. If you are a US citizen you can go without a passport. If you are not a US citizen you can enter with proper passport and with an US visa.
You can enter the US without it only if you have other proof of your citizenship and identity. If not, you need your passport.
I am tempted to respond by saying that I don't need a passport for anything that you do. However ... You do not need a passport to enter Canada, but you might experience difficulty getting back into the US without one.