Welcome from the Netherlands.
It might help to look at stuff you feel you could need for your stop motion movies. Some buildings, trees and such can always be usefull. That's kind of what I am selecting my purchases for: wether I can use it or not for my stories.
And to answer your question: nope, I don't have a seperate room for my playmobil. Though I must say it does limit my space for it. At the moment its all stored in closets and drawers in my room and at the attic. Still living at home with my parents but when I move out I do plan to get a house with an extra room for my clickies.