For persons 15 years or younger, 5 years. For 16 years and older 10 years.
There might just be an expiry date printed in your passport.
NO
yes because it has not expired
No, you cannot. Passport must be valid.
NO.
If you only have expired passports, you cannot travel internationally.
You cannot travel anywhere on an expired passport.
No , you do not need a passport unless you are leaving the US.
Yes it should be on your passport.
You may eventually, but after tons of trouble you will encounter in the US.
You must always use a valid American passport when entering and departing the US even if you are a dual citizen.
Yes, but you will not be able to reenter the US without a valid passport. (source below)
Yes, in some cases. Many US customs agents only ask for U.S. identification, if you're driving or walking across the border. Since a passport is only ever issued to a citizen, an expired passport would be rebuttable proof of citizenship, which is better than having a driver's license (which can be obtained by a resident alien, in some states).