Jim, some basic info for you;
The 8,82 is the measurement of the lands to lands.
1918 would be the last year of WW1 and DWM is the manufacturer. I blew up slightly, I would be interested in a closer look at this marking on the barrel just in front of the date on the receiver?
I would clean the luger (gently) with some good gun oil, be very careful if you take the grips off, as it is easy to break or chip them.
Overall it is a nice ensemble / rig!
Welcome to the forum!
Ed