"the technique book is wrong in that the second and third step are the same height."
Guess what. NOWHERE in the book does it say that.
"Quite unnatural and should start to lower at the end of step two."
Depends on what you mean by "lower" If you mean "decrease altitude", then yes you should. If you mean dance a classic lowering action in the leg and foot, then no, that is saved until the end of step three - which is what the technique does tell you.
"It was explained to me that if you follow the officiall book. you will climb onto a flat topped platform and lower over the end of it."
Nope. That only happens if you take an disingeniously simplistic interpreation of the book. A beginner could be forgiven that. A skilled dancer cannot.
"With Len you go up the slope and down a slope instead of flat across the top."
Len's description is clearer, yes, but he's actually describing the same thing that the offical book is specifying. He just eliminated the potential for confusing intermediates.
"Interestingly on another subject. The Whisk. He wrote that if the lady keeps the head to the left throughout a better Whisk in the Waltz can be performed. You know what he was right."
That's true of almost any promenade figure, at least as a learning exercise. Many of the old time teachers had the lady keep her head left in all promenades, until she learned to fill out the promenade shape. Only later did they introduce the head turn. Try it in your next practice - dance the figure a few times head left, then have the lady turn her head but keep the same feeling as when it was left.