He's focused to point the he almost killed himself once.
That is vdry good in fact. It means that your dog is a true working dog. Make the ball your main tool in training and forget about the existence of prong. I'd recommend you to study NILIF principles:
He said "Most attackers use guns now
Your friend is correct. Just forget about it, an average street agressor simply wouldn't bother to approach you, but you may meet many wiked people walking as gangs and your dog should show confidence and be obedient not to attack. Barking makes many to retreat, anyway.
In order to succed in something much more serious than so called "PPD training" it would be better to be involved in a real sport. Look for Schutzhund club, visit not just one, but a few, become their member. Once developed in Germany, Schutzhund clubs are available almost in every country of the world. Read more about it:United Schutzhund Clubs of America
Schutzhund obedience could be trained in your local club.