Wayne is a great guy and has tons of good solid information in his FAQs.
no doors or windovs so it all good
I recall Wayne saying that you need at minimum 1m (metric for you my European friend!) of uninterrupted wall on both sides of the cornerhorns.
how much in front of the listeners should the forward axes cross?
Wayne will link to the proper FAQ piece but I think he said ~1m.
have you got an oppinion on how much power they need to sound their best?
All Wayne's speaker's are fantastic in that they are high efficiency so they run well with low power tube amps (5W) and class A amps (10W) but at the same time they are high power, 'pro'-type speakers so can take 100s of watts and sound super clean doing it!
as i am in denmark i would like to just buy the crossover from you, is that possible?