Welcome to the forum. I hope you will keep us informed on your use of the Lehmann recipe (and any others as well) in Cologne.
You are correct about Tom Lehmann advising against placing the salt in direct physical contact with the yeast, at least for more than just a very brief period (I suspect he knows that today's hardy yeast strains can tolerate some physical contact). He also feels the same way about sugar. The main reason is that both salt and sugar are hygroscopic (they absorb water) and tend to extract fluids from the yeast through the cell walls by osmosis. This can degrade the performance of the yeast. In a professional setting, Tom suggests that the salt and water be dissolved in the water in the mixer bowl. This allows the salt and water to absorb water directly and not from the yeast. I think that Tom would also approve of combining the salt and sugar with the flour, even though they won't dissolve quite as well using that approach.
As to the whey, my use has been in dry form. I bought mine from a store that sells such items in bins. Professional pizza makers who use whey buy it from suppliers of baking ingredients. It is a baker's grade whey and may be somewhat different from the one I use.
I suspect that Peter Reinhart himself will tell you that his Neo-Neapolitan pizza will not be as good as one made using a good imported Italian 00 flour, even as adapted for use in his own recipe. His recipe is directed mainly to home pizza makers who do not have access to 00 flour or who do not choose to venture beyond using all-purpose flour, which is available everywhere. I don't know if the Caputo 00 flour is available to you in Cologne, but if it is, you may want to try it in your Neo-Neopolitan pizzas, especially if you can do it in a very high-temperature oven. I think you will see a noticeable improvement.