No, you cannot enter the US without a passport.
No, you cannot re-enter the US without a passport.
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.
No, you cannot enter Canada with an expired US passport. You must have a valid passport to enter the country.
no you need a passport
Yes. Recent agreements allow for US visa holders to enter Mexico without additional documentation -- besides the passport, that is.
As long as you have a US visa with you, you can also enter Mexico.
No, you cannot leave the US without a passport.
No, you cannot reenter the US without a passport.
Yes. You always have to have a passport that's valid past the return date when leaving the US, since you can't enter the US without a valid passport.
If you hold a valid Canadian Passport, yes you can enter the US from an international destination.
Yes, with a passport you can fly from the US to anywhere.