go to another country
No.
No, not in the sense that a person can be legally pursued or have credit denied due to the credit history in another country. However, if the person has had credit problems with a bank that has locations in another country, they can be denied banking privileges at that institution, which may create other problems
If a co signer can qualify with their credit, they can be from another country. They generally have to be present in order to co sign a loan, however.
the letter of credit is opened only for one business with a certain amount
You could try with PayPal
CRA's in the US, report the credit history of transactions made only in the US. Therefore credit history from another country would not show up on a report in the US. This does not prevent a prospective creditor from requiring confirmation of the person's previous credit history.
A foreign tax credit is a credit for anyone who has worked in another country. Foreign trade credit is an insurance against currency changes for businesses that sell products to foreign countries.
Unless you work for an attorney or someone who can legally pull other's reports, it is illegal and not easy to pull another persons credit report. You can't legally do so.
Actually if you add someone as an authorized user on your credit card, THEIR credit will go up but nothing will change with your credit. You are giving them the benefit of your positive credit history.
No, you can not give credit that you have to someone else. You can loan someone money or your credit card, but you are still responsible for paying the credit card company back.
Someone is able to get a credit card with 0% APR if they are switching their main account from one bank to another. These sorts of accounts are often offered to encourage new customers.