The parent that is in the child's best interest.
Yes, if there was no custody order filed. Please see link below.
see links below
No you can not.
Yes, but he could file for custody. Not tomorrow, nor next week. Take a month and prepare. see links below.
No threats needed, she has sole custody see link below
Child custody modifications may only take place through order of the court, however if you haven't seen your child in years and have been completely absent from their lives physically and monetarily, the other parent may seek to have your parental rights terminated based on the same.
After such long time it would be if the legal guardian is unfit. They would have to see to the child's point of view who has not seen her parent in 10 years and do not know him. Most likely would the parent get visitation and eventually shared custody. Eventually he has the chance for sole custody.
If the current custodial parent is not willing to relinquish (or take), custody, then you have to retain an attorney and have it taken before a judge.
IF THE MOTHER HAS SOLE CUSTODY
If the mother has the full custody then she can take the child, and she can get the child support. If she doesn't have the full custody, then she is not allowed to take the child without the father consent, but she still can get the child support.
yes
If, and only if, she has legal MAIN custody of the child, then yes.