As long as it is domestic travel (within the U.S.) children do not need ID as long as they are traveling with an adult who can present ID. If the child is traveling alone and does not have an adult who can present a valid ID at check-in, then the child will need to provide ID. Any Government issued form of ID should suffice. I would recommend checking with the airline to be sure. This answer applies to air travel only.
A child may need a birth certificate, or social security card. This is mainly just to prove that a child is yours. Most children don't need much beyond that.
You need photographic ID for ANY flight!
Yes. Passport or another kind of ID.
No
well its a good idea to have your valid Driver's license or State ID on you, but to travel within the U.S., you are not required to have any documentation.
you need to check with your airline - most require passports
Of course. You will need a valid passport.
No you need a Federal ID such as drivers license, passport or militay ID.
A passport (air travel) or ID/birth certificate (land travel) and some money to spend are all you need.
Not unless you are the driver.
A government issued photo ID. A driver's license or state ID is the most common.
No but they need a passport if they live in Canada.
You will need a passport, visa, and American Visitor Insurance.