Any reputable dog training includes training for the human as well. Training a dog using any method is hard to do successfully. I feel your opinion is somewhat based on negative personal experiences. Good training centres are an extremely good option in certain circumstances.
I feel we are...
Prey drive isn't a myth. Some dogs like chasing animals more than others? How is that statement slightly controversial?
Dogs getting a 'taste' for blood is, but dogs like doing fun things and if they have enjoyed killing birds in the past they will be more inclined to do it again. I don't...
Well obviously your current situation is not a viable option! Two attacks in less than four months is awful, it will only be worse once your dog is fully grown and figures out that duck tastes good. You need to create separate runs for the animals or get rid of one of them, simple. It doesn't...
What you need and what your ducks can technically get over are different things. Try your idea see if it works, if they work out they can get to the other side build it a bit higher.