It doesn't matter. Step parents have no legal rights anyway. The problem you are going to have is explaining to the child who these men are. If the legal husband wants to be called a stepparent, then all is well. If not, he does not have to be anything to the child.
Then you are not legally married.
He can not get legally married to anyone until he is legally divorced from you.
No. If the other person is legally married to another person in another state, then your marriage is not valid in the USA. You can have be legally married to one person at a time.
Yes. If the marriage license was legally obtained and the ceremony legally performed the couple are considered married from the moment they are pronounced "husband and wife".
No
Not if he is still legally married to you.
If you get married, yes, you can live with your husband and you are considered emancipated. Getting married a 15 is not allowed in many states, you have to be at least 16 with parental consent. And for under 16, those states that will allow it often require a court order.
Unless the stepfather has legally adopted the children, he has no built-in legal right to them.
If you are legally married, you are considered an adult.
{| |- | If you are legally married, you are considered emancipated. The age of your husband does not matter. Be prepared to present a certified copy of the marriage license. |}
No, they are divorced.
Sorry to tell you But You will always be legally married until you get divorced!