Hi and welcome to the Luger world.
Reworking usually lower the $$ walue but in your case the sentimental value is what really counts.
For me, something like that from my late father would be far more valuable than any high $$ "collectors" item.
Looks like a beutifull pistol, and retrofitting could have something to do with ammo avalibility at the time.
9mm or not, you should be able to confirm with a pencil. If the "eraser" end fit in it,s 9mm. im told.
The small tool is a reloading / take down (skrewdriver) tool.
You fit the hole over the knob on the side of the mag (skrewdr. end up) and use your thump to push the fallower down to make it easyer to reload the mag.