Yes
To fly into Mexico you HAVE to have a passport. As of right now the only way you can get into Mexico without a passport is by land travel, but that will change as of Summer 2009. As of Summer 2009 you will need a passport for any land travel into Mexico and Canada.
A passport if flying there or a driver's license if going by land.
A passport (air travel) or ID/birth certificate (land travel) and some money to spend are all you need.
No. A passport is sufficient to travel to Mexico. A birth certificate is not valid for international travel. If you are traveling by land or sea, then you can enter Mexico with a US passport card, "enhanced" drivers license or "enhanced" non-driver ID.
If you are a resident of the US, you need a passport to travel to ANY other nation and to return to the US.
Yes. You only need a birth certificate and or ID.
If you live in Mexico then no.
Yes
No, for international travels, you really need your passport. However, if you plan to land or sea travel to Mexico or Canada and you have your License and your Green Card and Birth Certificate, then you can but you still need the passport when you get back to the US for easier travel.
No. New Mexico is part of the United States, so you don't need a passport. :)
Yes, you can travel by land or sea from the United States to Canada, Mexico or the Caribbean and back again using a U.S. Passport card. To travel by air or outside of North America, you will need a traditional Passport booklet.
You already need your passport to go to Mexico as a U.S. citizen entering from the U.S.