I believe this particular decoration is the pre-1917 “ Pie-Slice” suspension devise variation. The cases is from one of the jewelers appointed to the Crown in Berlin and fitted to the award. It is probable that this particular Pour le Merite was worn since it comes with ties along with the ribbon. PLM’s with Oak Leaves were personally awarded by the Kaiser. Those awarded a PLM were required to wear it at all times, when in uniform or civilian attire. So typically if awarded this medal a second would be purchased as a wearer’s piece and the original put away. When I purchased this from another advanced collector some years back there was no award document so this original Pour le Merite with Oak Leaves is likely a wearer's copy.
The presentation case is 6X3X1.
Unknown. I purchased it from a dealer in Berlin a number of years ago.