Behaviour in and out of home:
Dogs are pack animals and when they're at home, they are safely in the den. The home environment becomes predictable and even boring for dogs, so coupled with this feeling of safety the lack of stimulation leads to some dogs lazing around the house (which is not a bad thing).
When they are out and about, the environment is new and stimulating. There are many potential threats, and dog's, generally, feel it's their duty to protect their people, not just themselves, so there's a lot going on for your dog.
The behaviour you describe is not of fear, but the alertness and protectiveness of an alpha dog. Walking in front of you is an assertion of his authority as the leader (which may or may not be a problem).
He walks with almost his entire weight over his front paws; ... he has his ears up and tail stiff ... he will lunge at basically any moving object ... He pulls on the leash, and essentially refuses to walk anywhere except in front of me.
Dogs communicate with other dogs by marking their territory. They enjoy discovering new smells and cocking the leg is like leaving a calling card for other dogs.
He smells and urinates on everything, often kicking dirt when he's done.
Most animals react to eye contact, particularly if you are staring close to his face, he will aver his eyes to avoid confrontation with you. By ignoring you he is challenging your authority over you, by avoiding your gaze he is actually submitting to you in that instance (which is good).
He completely ignores me, so badly that even if I grab him by the snout and point his face at me, he keeps his eyes glancing sideways
The first steps:
The way to overcome this is to reassert your position as leader of the pack, your dog needs to know he is the lowest member of the family pack (last after all the humans). This can be done with a number of simple techniques within the home to begin with.
- Feed your dog after the people.
The family should sit and eat their main meal and finish before feeding the dog. The dog should never be allowed titbits from the table.
Lower pack members eat last.
- Have your dog sleep furthest away from your bedroom.
Highest ranking pack members have the, literally, highest places to bed and the lower the pack member the further it's position from the pack leader. Ensure any family members bedrooms are between you and your dog's bed.
- Do not allow the dog on furniture
Same principle as above, the dog cannot share the same privileges as other family members.
This may sound harsh but with a pitbull cross he is a naturally dominant dog. I love large dogs and have owned a rottweiler and dobermanns. With these breeds, it is vital to retain the position of pack leader.