Yes, if you have a US ID and cross the border by car or foot, you will be OK.
No.
No. You need an ID or birth certificate in case you cross the border by land, or a passport in case you take a flight into Mexico.
No. Going beyond border cities such as Tijuana, Mexicali or Juarez (the later is highly unadvised to visit), you will need a passport.
Now Canadians and Americans need passports when visiting each other.
Canada requires a valid passport to enter the country. In the past one could use a driving license or other ID, but today only passports are acceptable.
Border Patrol can ask for ID when they have a reasonable suspicion that a person is in the country illegally.
You need an American ID, birth certificate or US passport. Note you don't need anything to cross into Mexico; however you will need any one of these documents to return to the United States.
If you have an ID and birth certificate, you shouldn't have any problem re-entering the US.
Yes, the three of you will need a passport.
No you cannot you must have a passport/id
The ID number on a California ID card is a unique combination of letters and numbers that serves as a personal identification code.
There are many ways one can get a California idea. One can get a California ID by being a citizen of the state of California and visiting a DMV location in California.