Looking for a bit more information about this K date and holster. (34 pictures)

[LugerNewb]

Hey you guys, I was poking around and found my grandpa's Luger at his place and he gave it over to my dad (something he'd been meaning to do but lost it). He served in WWII, brought it home, and when I asked him about it, all he said was "Its original owner couldn't use it any more" so I assume he got it off someone in the field. Unfortunately he won't talk about his war days (which is a shame because it's a tragic loss of breathing history, but I understand the reason) so I don't know much about this. I know it's a K date, which makes it a 1934 manufacture, and I know Mauser made it, but beyond that, not much. All the serials match except the magazines and the inside base of the barrel (so close...), but it's in relatively poor aesthetic condition upon close examination.

The holster is in good condition, just a bit scuffed up. The belt is in terrible condition, as it seemingly fused with itself and had to be worked apart (you could see where bits of it had melted together though, so it's not like it could've been saved), but it's still pretty cool.

Specifically, I'm most curious about:
- What style of holster it is.
- The potential meanings of the markings on the holster (notice the damage in 7? Wonder what they decided to gouge out? Guess we'll never know).
- Any kind of information on the magazines (16 and 17)
- Meaning of the markings in 25
- What the part in 29 is called so I can mark specifically what it is that doesn't match (just for my records, not planning on selling this). In that same photo you can notice two obvious gouge marks too. This gun has seen better days.
- What the 'D' marking on 33 means
- Opinions on rifling in 34 would be appreciated, though it's probably too hard to tell. Was the hardest thing to photograph.

Also any and all knowledge on this thing is appreciated, as I don't know much about it and would like to share with my dad and granddad. Also advice on restoration and an estimation of value would be appreciated too. My dad wants to bring it to a local gunsmith but I'm afraid they'll conveniently 'lose' it and it'll never be seen again (at least not by us...) so I figure if I could attach some value to it he might be more careful about who he brings this thing to for restoration/safety checking (to see whether it's safe to fire). He thinks it's only worth a hundred or so bucks, I think it's worth several hundred at the least so I'm not real convinced it'd be returned, but maybe I'm just paranoid.

Anyhow, thanks for any and all help!
- Newb