This is a very complex question. You need to consult an Alabama attorney. Part of the answer will depend on which state issued the initial chid custody and visitation order. The laws of that state and the contents of the child custody orders will help you decide in which state you should be filing for modification of custody. If the Alabama court was the court that issued the first order, it is possible that your Alabama court has retained exclusive jurisdiction over child cutody of your minor children. If the initial child custody and visitation order was issued in Florida, and the children have been living in Florida since 2008, then you will probably need to file in Florida. You mention a number of facts that would be important in obtaining a favorable decision. First, though, as you have gathered, you must determine with the assistance of a local attorney in which state it is more appropriate that you want present your facts. In a complex situation like this, sometimes the courts of both states must be involved and confer. This might be applicable here if Alabama was the state which ruled first in regard to your children.
The amount of detail in your question surely indicates that you understand how complex your particular situation is and the fact that two different states are now involved. As indicated in the initial answer, the question of jurisdiction is key here. If the court granting the divorce issued a child support/child custody order, that court retains jurisdiction, absent a formal transfer of jurisdiction to the Florida court. I could not determine from your facts if a valid marriage ever existed in the state of Alabama and was terminated by an Alabama court order granting a final decree of divorce. If the children were born out of wedlock and there was no valid underlying marriage, then it is possible (likely) te state of Florida would have jurisdiction over the welfare of the children.
You very defintely need the services of a family law attorney to untangle this situation. It may be best that you retain an attorney in Cullman and have the Cullman attorney contact a competent lawyer in Orange Park and work through this issue jointly.