As long as you have the legal documentation to prove you are married your marriage shoud be held valid in any other country. (there are some exceptions; for example in some countries polygamy is legal, but not in others)
No, you can only be married to one person at a time.
If the marriage is legal in the other country, they are married everywhere in the world.
He married in another state and didn't know he was still legally married to someone else
If you are married under the laws of another country, you are considered married throughout the world. If you have one wife, you cannot legally marry another. It is bigamy and is against the law in the United States.
Of course not! You can only be married to one person at a time anywhere in the world.
You are already married, you can't apply for a license. The US will recognize a valid marriage in another country.
There are multiple specialties available. There is a shortage of nurses in the US at this time, so you will have a number of options to choose from.
If the marriage was legal in Jamaica and registered there, then, yes, you are legally married in the U.S.
He shouldn't, but he CAN do whatever he wants.
I don't think so.
Not unless they themselves are registered in court as an American citizen.
Your marriage in Pakistan is valid in the US, if someone is married in another country, they cannot get married again in the US or vice versa. The second will be void.