Am I right in thinking that Kulm is the German spelling for Chelmno? and that most of these other villages are located in the immediate vicinity?
You are right and in the right area.
It's a gmina-county in which there is a village Święte: en.wikipedia.org/wiki/Gmina_%C5%9Awiecie
I saw a village near Chełmno called Grubno, which is probable your Gruelno.
At the bottom of the above links you have the surounding counties and villages. Work around these to locate your villages.