I'm not very good at these marks, but until a Luger expert takes a look, I'll offer the following:
The crowns over letters usually are "proof" marks applied by government testing
agencies to indicate that the barrels, chambers and mechanisms have been tested
and have passed by firing nitro powder (as opposed to black powder) test rounds. I
don't know which government, but unless your Luger is a contract gun, most likely it's
Germany.
The figure at the right looks like an eagle with a star over it, and I'm afraid I just
don't know. However, it may indicate either (1) a country other than Germany
(the eagle isn't recognizable to me as a German-style eagle) as having accepted
the gun, or (2) it may be a form of German repair proof.
The entwined letters on the toggle link are "DWM" for Deutsches Waffenfabrik und
Munitionswerk, i.e. German Weapons and Munitions Company. They produced the
early Lugers (yours is dated: 1915). They made other weapons as well. The
two-digit numbers are parts numbers. Hopefully, all the parts in your gun are
numbered the same, meaning it wasn't put together from left-over or replacement
parts, but is the original piece.
Looks nice. Enjoy it. Is it a "prohibited" Luger, or does it have a longer barrel. It might help to see a picture of each side of the whole gun.