This will depend on where you want to travel. If only within US then you need a valid ID, if international travel you need you passport, visa and other requirements like immunization and such.
A US citizen does not require a visa to visit Dubai, only a current and valid US passport. Proper visitor documentation will be granted, free of charge, upon arrival of US citizens.
No.
A valid picture identification card.
It is safe. Hundred of US citizen travel daily to Serbia.
Anything that is not restricted by the TSA to be shipped with you.
Hawai'i is a US state, therefore no passport is needed for US citizens to travel to or from Hawai'i. Hawaii is part of the United States. Therefore, if you are a Citizen or a Permanent Resident(Green Card holder) you won't be needing a passport to go there. DL will do.
The right to travel with a US passport is one benefit of being a citizen of the US. US citizens need a passport to travel to other countries.
May be Afghanistan is the only friend country for USA, in which US citizens need Visa to travel.
Passport is a requisit.
Passports are not required for travel inside the US. Anyway, non-citizens, legal or not, are not eligible for US passports.
no
It is becoming more and more important to provide yourself with adequate documentation. Many oppose it, but an internal passport document is getting closer to reality then US citizens are prepared for. The Department of Homeland Security will surely propose it soon.