Yes, he does.
does a citizen of Mexico need a passport to go from the us to Mexico and back? He is legal to be in us but not a us citizen.
yes
It is advisable to have a passport but a citizen of Mexico or the USA can do this with a drivers license.
Yes, you need a passport to go from the U.S. to Mexico because Mexico is not part of the U.S. If you were going to a U.S. territory and you were a U.S. citizen, you would not need a passport.
Yes, you do.
No not if your a United States citizen.
Yes, they do.
No. You need your US passport.
Yes. Not a passport per se, but you need an ID to get into the plane.
No. Both are in the United States. You do not need a passport to travel from state to state.
In none, with the assumption that you are already a US Citizen.
If you are US, Canadian or European citizen you can enter Mexico without the need of a visa.