Wheel bolts are the standard VW alloy/steel wheel bolts.
Wheel caps I never got to the bottom of the exact size when I had a set of Canteras previously.
You really need someone with a set to look at the VW part number on the back of the cap.
Oh, and if you'd rather not use the wheels - you know as they have no caps, then please sell them to me as I am looking for another set right now