United States of america

At the port of entry, upon granting entry to the United States, the department of Homeland security, U.S. immigration inspector, provides you an admission stamp or paper. If your admission stamp or paper form 1-94 contains a specific date, then that is the date by which you must leave the United States.

You should contact the immigrant visa unit of the U.S. embassy or consulate that issued your visa.

The fee paid is an application fee. Everyone who applies for a U.S.  visa anywhere in the world must pay this fee, which covers the cost of processing your application. The fee is non-refundable regardless of whether you are issued a visa or not, since your applicating was processed to conclusion.

No. since you have been authorized, you will be able to remain in the United States during your authorized period of stay, even if your visa expires during the time, you are in the United States.

No. if your visa is still valid you can travel to the United States with your two passports, if the visa is valid, not damaged, and is the appropriate type of visa required for your principal purpose of travel.

Persons holding visa valid for multiple entries may take repeated trips to the United States, for travel for the purpose, as lo0mg as the visa has not expired.

You must possess a passport valid for travel to the United States with a validity date at least six months beyond your intended period of stay in the United States (unless country-specific agreements provide exemptions).

You qualify for the Visa Waiver Program if you are a citizen of a Visa Waiver Program country, possess a machine-readable passport, are traveling for temporary business or a visit of less than 90 days, meet other program requirements, and have obtained an authorization through the Electronic System for Travel Authorization (ESTA).

Yes, for most applicants. There are only a few exceptions to the interview requirement. The following applicants generally do not have to appear in person:

I have a nonimmigrant visa that will expire soon, and I would like to renew it. Do I need to go through the whole visa application? 

Each non-immigrant visa application is a separate process. You must apply in the normal manner, even if you had a visa before and even if your current non-immigrant visa is still valid.

The validity of a visa cannot be extended regardless of its type. You must apply for a new visa.

As soon as you receive your visa, check to make sure all your personal information printed on the visa is correct. If any of the information on your visa does not match the information in your passport or is otherwise incorrect, please contact the issuing authority (i.e., the) immediately. The expiration date of your visa is the last day you may use the visa to enter the United States.