Fear? Aggression? or Territorialism?

Louie living in his equipment shed on a crawfish farm in Louisiana (July, 2011). Louie was living on crawfish and roadkill, he weighed 39 pounds and is heartworm positive. This is a link to Louie's background - https://www.crrow.org/rescues-that-stay/louie/
Louie came to live with me on October 30, 2011 and in a few words – he was a case! Louie only had an On/Off switch. Louie was either at full speed, running frantically from door to window to door to me to door to window. Or he was sound asleep on the couch. The couch was the only place he would crash. He was 2 years old and could not be left unattended so when I was not on the main floor of the house or with him in the backyard, he had to be crated. When he was crated he would SING! And I mean sing at multiple octaves, at a volume that would wake not only me but everyone within 5 miles of my house!
So what is the issue?? He was a stray and appears to have been on his own from early in his life. He has only been living inside since August and acts like a wild animal looking for a way out. When he is outside he is pacing the fence lines at full speed watching for game, barking at every noise and just generally on overload the entire time. Is this fear or prey drive?
When someone comes to the house or walks past the fence he jumps, barks at the fence. When someone comes to the house, he runs frantically around the house trying to get away and periodically lunges at guests after they have been here awhile. Is this aggression or territorialism or fear?

Louie showing off his favorite toys and working on his "stay" command. Stay, Leave It and Down are extremely tough for Louie. Louie now weighs about 64 pounds.
Well, it has been and continues to be a journey with Louie. He is making improvements, we have made some headway but we have a long way to go. Louie and I are approaching 6 months of being together and we have a long way to go. Louie is still technically a foster and maybe always will be, I am not ready to make that decision. In this blog, I will attempt to chronicle our journey to this point (April, 2012) and forward. So the posts will be a combination of what we have learned in the past 6 months and what we encounter as we continue. I hope in the end this will be helpful to a few people, but mostly I hope it will be helpful to Louie and me as we forge ahead on his training.