Yes I think 9640 is serial number. There is a "point" after it, to answer your question. I don't know about the Wernig numbers, his guns are not common today so comparison is not easy, and neither are conclusions.
15.? is bore measurment in mm. The two marks on the barrels in picture 3 seem to be proof marks. The upper seems to be Carinthian coat of arms and the lower the Eagle; a detailed macro photo of the eagle showing more detail should narrow the period of proof. I can't see the EF monogram which is for preliminary proof.
As for the WP stamp, I saw it under one Wernig barrel.
I am looking forward for more Peter Wernig guns to surface in the future - and other early Ferlach guns as well...
Cheers,
Jani