I can confirm that any activity is along the red light windows in Nieuwstad.
I was there before Christmas and had a walk along, but did not partake.
It is the usual mix of pneumatically enhanced hookers from the east of Europe, a few locals, some offering S&M and a few more mature ones.
I asked one of them the rates - the usual 50 euros for a quickie, and 100 for 30 minutes.
The area is safe, so no worries walking around