No. Having a visa for the US doesn't grant you the possibility to enter Mexico; you need the corresponding visa from Mexico.
You only need a valid passport to enter Mexico.
If the marriage is legal in Mexico, it will be held legal in the US. However, it is not legal for anyone under the age of 16 to get married in Mexico.
No. If you enter Mexico by plane you need a valid passport. If you enter Mexico by land however, it will not be much of an issue; however on your way back to the US you will have to show at least an ID or birth certificate.
No
You are able to. I was a permanent resident with a green card( actually pink) and i went to Mexico and Canada with it.
As long as you have an American passport, you can enter Mexico. Problem is on your way back to the US. Without a valid proof of citizenship, you will not be abe to return to US soil.
Your birth certificate will not help you. You can enter the US from Mexico with an "enhanced" US drivers license, but only if you are traveling by sea or land, not by air.
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.
As long as you have a US visa with you, you can also enter Mexico.
To gain Arizona and New Mexico from Mexico
Mexico