Chapter Fourteen: proof that a picture is often worth a thousand words. All we needed was a map (which also exists, so not sure why we have the text, too).
There are several possible estimates for the number of Elves in Beleriand. I used to know their details, long ago, but now I just remember that even the smallest one was > one million. Most were not Noldor, however. (In general, reading the musings here keeps giving me a sense of deja-vu, like 'oh, I remember researching this once; it was a lot of work, pity I forgot what I found'. But the good news was that, if I was doing the research for a story, there was usually a wide-enough range of interpretations that I could pick and choose the one I wanted.)
I think Dorthonion is 180 miles east-to-west, if you translate the leagues. But of course on some maps it appears bigger. (Polish also has it in the e-w direction, btw, or rather 'sunrise to sunset': our directions are named that way, also 'half day' for south and 'half night' for north)
Regarding Thingol, yes, sexism. But also, there is a bit of a tendency to describe several of the Elvish rulers as the wisest and tallest. I remember Turgon in particular. (I do not judge his wisdom highly, myself.)
I find Feanor's death both personally satisfying (because ha!) and narratively odd. Oh, and it's possible that Maglor was repentant too.
(I think the Silm has him be the one to save the kids later? Although I know it was Maedhros in some other versions. And doesn't he argue against stealing the jewels at the very end?)