I just thought I should update this thread with results.
It appears that we have been able to get this dog to understand that people and kids are okay. He loves our kids now and only barks when he doesn't know who is there. When he sees them he becomes happy.
He seems to just be overly protective of the house in general. When he thinks he hears something at the door he barks or growls. We have gotten him to shush up quickly though and if we tell him its okay, he generally quits immediately. What we haven't been able to do is get him to stop barking all together. There are some neighbor dogs that bark so he joins in. I try to catch him and bring him inside as soon as he starts to minimize the behavior.
As for aggressiveness in general, he is not. He is just protective. He doesn't bite and doesn't mind kids. He doesn't like people to come to him, he wants to come them first to check them out, then he is fine. I feel safe with him and our children.
What we did to correct any behavior is not very cut and dry. We did a lot of socialization in many different settings. We also made it clear that the children were more important that him and that it was unacceptable to growl at them. He still growls at dumb times sometimes but we realized that there is nothing to it really. It is like it is an instinctive growl and then he comes to his senses when he sees them and wants to play.
Hope this helps someone else make decisions.