Translation:How many men and how many women are getting on the Dutch airplane?
Is it necessary to specify "hány" twice? Can I just ask "hány férfi és nő?" and be understood?
If you want to emphasize that you need to know the totals separately, this is the way to ask. Yes, you can ask "hány férfi és nő", but then you might get just one number as an answer.
Szall fel is confusing, particularly when an aeroplane is involved. Szall le = landing and szall fel ought to mean taking off. You often use szall be to describe getting in but in this instance you use szall fel to mean getting on or, as described by Judit, boarding. All very confusing.