Can I legally leave my husband, take my kids, and move back home to another state or would that be kidnapping?

If there is no court order in effect, than you are within your legal rights to take your children out-of-state.  However, your husband can go to court in GA and obtain an order which will require youto return to the state.  If at that point you don't return or return but again leave with the child, you can be charged with parental kidnapping.

The best way to obtain legal custody of the children is to go to court first.  Taking a child from their home and where they were born to take them to live in another state is not a good idea either now or in the long run, insofar as a custody battle is concerned.  What you wants to do is get a temporary order from the court on custody and visitation.  It will be temporary because a final decree will be issued upon divorce.  The court will consider the bests interests of the children in making its determination. The court will look at the age of your the children, the relationship of the parents and children, the present living situation of the children, etc. 

Note:  You could file for custody once you establishes residency in FL but that will take time.  In the meanwhile, as previously stated, your husband should file in GA.  You would then be required to return to GA.

Right now, you need to consult with an attorney in GA (even if you later decide to file in FL).  See what they advise as to how best to pursue all of this.