There is a good discussion of Navy Luger marking in this post:
http://forum.lugerforum.com/showthre...ghlight=anchor
There were addressing a question about the WW-II era, but describe how Weimar era re-worked Lugers were marked by the German Navy.
The "N.339" would be a unit property mark associated with the North Sea command.
The "Crown/N" or "C/N" marking is a Nitro proof marking indicating that the pistol passed high pressure testing.
The Weimar era guns were manufactured after the end of World War I and before 1929 when Mauser purchased the DWM Luger manufacturing equipment and tooling.
Many WW-I Lugers were refurbished since Germany was inhibited from re-arming after WW-I.
I'm just starting out researching and understanding Lugers. This site and Jan Still's forum site have tremendous resources, and are frequented by international class experts.
The Navy Lugers are more rare, and your gun has not been "messed with" (refinishing reduces it's value). It looks to be in very good condition, as does the holster.
The papers add to your gun's value also, giving it provenance.
After ensuring it's not loaded, you can disassemble it to verify that all the parts have matching numbers (most will have the last two digits of the serial number, or the entire number). That makes it more desirable and collectible.
The magazine bottom looks like WW-II vintage. It's not likely to have a matching number on it's base.
Be very careful disassembling your gun. It would be a good time to ensure that it's clean and that parts have a light oiling with a rust preventing oil like "RemOil". I would tend to store the gun and holster separately.
You can get an idea of what dealers are asking for similar guns by looking at sites like Simpson's:
http://www.simpsonltd.com/