Lots of stuff came from the radio show, I believe. The classic Fleischer cartoons of the 40s added to the character as well.
Yes, the radio show introduced the characters of Jimmy Olsen, Perry White, and Inspector Bill Henderson, as well as introducing kryptonite, the famous opening narration, and most of the catchphrases associated with the character (like "This looks like a job for Superman" and "Up, up, and away," in order to verbally describe things that the comics would just show visually). The
Daily Planet originated in the daily Superman newspaper comic strip (changed from the original
Daily Star because the strip was carried by several newspapers that had rivals named the
Daily Star).
As for the Fleischer cartoons, they pretty much introduced having Superman fly instead of jumping, although the comics and radio show had often been ambiguous about that; and they're also the primary source for the iconic image of Superman changing in a phone booth, something he never really did in the comics except on occasions where writers wanted to make fun of the cliche of Superman changing in a phone booth. Plus Sammy Timberg's Superman theme from the Fleischer shorts was the original template for most subsequent Superman themes including John Williams's.
Anyway, I brought up the novel as an example of '40s tie-in novels to radio shows. Given that it was written by Lowther, the book probably counts more as a radio tie-in than a comics tie-in.
I went on a 15 year movie binge when I was young spent a lot of time talking to movie buffs, and none of them ever mentioned tie-in books other than maybe a few sci-fi flicks.
I once owned a novelization of
Forbidden Planet. It was interestingly different from the movie, since it was written in epistolary form as a couple of different characters' first-person journals, and so it contains a lot of stuff that wasn't in the movie and leaves out a lot of stuff that was, because the viewpoint characters writing the journals weren't there to witness them. I say "interestingly," but that format made it a bit unsatisfying for me.
I'm finding it very hard to reconcile Discovery with the rest of Star Trek right now.
Honestly, so am I, in some ways. I also had trouble reconciling a lot of things in earlier productions, like many of the movies and a lot of VGR and ENT episodes. And there are things in TOS itself that I've always had trouble reconciling. But my opinion doesn't count. Future productions will presumably treat DSC as part of the same continuity as the rest, just as they've done with all the previous series and movies. I've learned to accept that reality.
Heck, part of the reason I became a science fiction writer was so that I could create my own original universes and give them the consistency and credibility I so rarely got from
Star Trek and other SFTV. And yet I still end up with imperfect continuity in my original fiction, despite my best efforts.
What Happened to Mary (1912) is often cited as the first movie novelization, although technically it ran as a magazine serial first before being collected in book form. But many long-forgotten silent melodramas were novelized, enough so that you actually had writers churning out several of them in their careers, while the word "novelization" is possibly older than movies. (There were once novelizations of stageplays.)
But what about
original prose fiction tying in to film or radio series? The
Shadow pulps probably qualify, since they didn't just adapt the radio show, but were they the earliest examples?
Yes, that was a bit of a headscratcher I'll admit. Probably my first exposure to a discontinuity. And I just accepted that because, well, I had no choice. I knew the real world answer once I thought about it (that being films provided more resources for such things). And one of the novels I read at the time, was it "The Final Reflection" maybe, provided a possible genetic reason, similar to Enterprise's rationale. Ok, well, I'm getting off topic. 
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Probably a little more than mine as you are in the business. 
