If you are just going to visit him in the US, all you need is a visit visa (tourist visa) but if you are planning on making your home permanently there with him, he needs to apply for a K-3 spousal visa for you.
Providing it was done legally and was not a 'sham' marriage, yes, they can.
Yes, the marriage is legally recognized in the United States.
Yes
Marriage is a wonderful event. Yes, if a female US citizen legally marries a non US citizen in the state of Michigan, they are indeed legally married.
If the marriage was conducted legally in the other country, the US will recognize the marriage is valid.
If the marriage is legal in Barbados, the US will recognize the marriage as being legal.
Yes, a marriage performed in South America will be honored in the U.S., with the exception of gay marriage- which is not recognized in the U.S. If you mean a marriage in the U.S. between a citizen and an illegal, this marriage will also be recognized, but again, not for gay marriage. Be aware than simply marrying a citizen doesnt grant you legal residency
There is no requirement for the witness to be a citizen. As long as they are legally an adult it is sufficient.
As long as you are legally married to a US citizen, you are a citizen. it doesn't matter if you get divorced or not. YOU ARE A CITIZEN!
No. Every way of becoming legally in the country reqquires a fee of some sort.
If you were married in a ceremony and in a manner that is legally recognized by the government of the Bahamas, then you are considered to be legally married anywhere -EXCEPT- if you are a US citizen, and your marriage violates the laws or statutues of the state in which you legally reside ("gay" marriage for instance) it is not a legally recognized.
Your best option would be to leave the country, apply for a marriage visa, re-enter legally on the marriage visa and then get married.