@FreeDuck,
I've read that book and I agree that it's very good.
We've practiced those things. We've even gone further on a point of two:
That it's perfectly fine to be rude to an adult who tries to start a conversion with him or asks him a question or for help when Mr. B and I aren't around. That grown up should know better than to do that.
That if someone tries to get him in a car by saying they have a gun that he should yell "Then you'd better shoot me here" and run.
That if someone tries to grab him he should yell, hit, kick, scream, fight, pee on himself, poop on himself, vomit or otherwise do what ever it takes to get away.
We've rehearsed how to find a city bus stop and ask the driver for help if he's ever lost.
We've gone places and picked out people we thought would be safe to ask for help.
We have "safety questions" that have to be answered should anyone ever try to tell him that Mr. B and I sent someone else to pick him up (with the understanding that we would never send someone he doesn't know to pick him up).
We've never had a "stranger danger" talk, just a "danger" talk.