Yes you do.
Yes you would.
passport
Depends. If you are flying from Honolulu, you do not need a passport. However, Since Guam is technically part of the United States, you do need to show proof that you are from the US. (Photo ID, Drivers License, etc.) If you are flying from a foreign country, you will need to go through Customs.
If you are a US citizen you don't need a passport to fly within the USA (for example from Kansas City to Chicago), but you will need some form of official photo ID such as a drivers licence. If you are not a US citizen you will also need photo ID and a passport is best for this.
Guam is a protectorate of the USA, but is out of the country. I think you will need one. You can check at the post office.
If you are a permanent US resident, then you can enter Guam no problem. It is a part of the US and you do not need a passport or visa to enter.
I don't believe so since Guam is a US Territory. However, you should probably have one to be on the safe side. If your flight gets diverted by chance, you won't be able to leave the airport to go to a hotel.
Entry requirements for Guam are the same as for any U.S. destination. Although U.S. citizens are required to possess a U.S. passport, on a case-by-case basis, photo I.D. and proof of citizenship may be accepted.
Provided that travel is direct and does not include going anywhere outside of the United States and its territories, a US citizen or permanent resident does not need a passport to enter Puerto Rico. The same applies when visiting Guam, the Virgin Islands, American Samoa, Swains Island and the Northern Mariana Islands.
You need a passport to get a visa
You need a passport
Yes, if you have a passport card but need to travel internationally by air, you will need to obtain a passport book.