Dwarven Language, Culture & Lifespan

[Palanan]

Are there any notes or essays by Tolkien that go into deep detail on the languages and societies of the dwarves?

There are a couple very brief essays in The Nature of Middle-Earth, but I’m hoping there’s far more available in other sources. I want to know as much as possible about his thoughts on dwarves, but I’m especially interested in how much effort he put into developing dwarven languages.

[Keltest]

Khuzdul is one of Tolkien's most mysterious languages, in so much as what he actually made up of it seems to have never been written down in a form that was made public. I think theres maybe half a dozen words known that aren't place names? This was somewhat by design, since their language was secret to all non-dwarves no matter how friendly, and the finished works were presented as being historical documents compiled from the writings of the Baggins family, who would not have access to much more than that.

[Palanan]

Thanks. Are there any other sources which delve into the history, culture, demographics, etc. of dwarves?