Guam is a US territory and US Visa Policy also applies to the Guam visa policy. It means you can apply for a US visa for traveling to Guam. There is no separate (individual) visa for Guam.
For detailed information about US visas, you can check US Visa Policy.
Nationals who are eligible for US Visa Waiver Program are not required to apply for a visa to travel to the USA or Guam, but they have to obtain Electronic Authorization (ESTA) if they are arriving by air or sea. Visitors can stay for up to 90 days in the USA or Guam.
Electronic System for Travel Authorization is not considered as a visa, but it is a prerequisite for entering the USA by air or sea. You can apply for an ESTA from this website. ESTA fee is 4 USD and if your application is approved, then you will be charged an additional 10 USD.
Guam has additional Visa Waiver Programs for some countries’ nationals. Below nationals can travel and stay in Guam for up to 45 days without obtaining a visa or ESTA.
The above-mentioned countries’ nationals have to complete I-736 Form (available both online and on paper) before they travel and possess a non-refundable return ticket to their home country. They are not allowed to travel to the other parts of the USA (included the mainland) without a visa or ESTA.
Yes, you can travel to Guam with a US visa. Guam is a US territory and US Visa Policy also applies to the Guam visa policy.
No, Schengen visas are not valid for travel to Guam.
No, Canada visas are not valid for travel to Guam.
No, Guam doesn’t have its own visa policy. Guam is a US territory and US Visa Policy also applies to the Guam visa policy. It means you can apply for a US visa for traveling to Guam. There is no separate (individual) visa for Guam.
Visa-exempted nationals can travel and stay in Guam for up to 45 days without obtaining a visa or ESTA.
Your passport must be valid until your departure date from Guam, but it is advisable to possess a passport valid for at least the next six months for avoiding any issues.