As to the mysterious 'h' in script type, it is part of the serial number. They started in January with serial number 1, went to 9999, then went to 1a and all the way to 9999a, then to 1b and all the way to 9999b..... like that. My first Luger was a DWM, 1918, s/n 5076c.... which means that it was the 35,076th Luger made by DWM in 1918.
'ar' was the Mauser plant at Borsigwald, Berlin.
Originally, it would have had a blue finish, very rich and dark and lovely. Only the war-gods know what might have happened since.
The Russians had a special mark, looked sort of like a sloppy "X", that they stamped on captured materiel to mark it for Soviet use. If you look at it carefully, you will notice that it is supposed to be crossed Moisin-Nagants. I have this on a Luger. Problem is that they didn't stamp everything.
Even if you never find out the entire history of your rifle, you have a real piece of history in your hands.
Have fun!