No, and he is in big trouble. In the United States a person can be married to only one person at a time. If they wish to remarry, they must end their present marriage legally, by a court decree. If a...
yes
You can't get married until you have ended your first marriage legally by a court decree.
You get divorced first, unless you are in Saudi Arabia.
Yes David was married as in Samuel we read he was married to Abigail.