Time for some reading. Go to the top and download the FAQ's
https://forum.lugerforum.com/showthread.php?t=35479
Beyond that I am sure others will provide information
You do have a mismatched gun as all the numbers do not match
The slightly rusted magazine could use a little oil and maybe very light steel wool to clean up, but others may tell you to not touch it as magazines also have value and any alteration/cleaning will detract. Oil would be OK but any polishing perhaps not.
Do perform the pencil in the barrel to determine if 9mm or 30 luger and read on the forums here about ammo it likes.