Arnhem is my hometown!! Maybe we can meet?
553 Sqn, B-flight unites!!
There basically are no rules for wearing unform in public. There is a rule saying you're not allowed to impersonate an official by wearing current uniforms you're not entitled to.
Even as TA (Reserve Army), you officially have to have permission to wear your uniform to an official 'do'.
I'm not aware of any restrictions in wearing uniforms from 'back in the day' in public.
As for museums, you've summed up the biggest and most interesting! Well done on your homework!
There is an aviation museum at Soesterberg: http://www.militaireluchtvaartmuseum.nl/
(all in Dutch - sorry)
It's near Utrecht which is a bit out of the way. But Holland is small so it shouldn't take more that 45 minutes to reach from Arnhem.
At Deelen Airbase there's a museum from an aircraft recovery group:
Deelen is just north of Arnhem.
I hope I've been of help