A couple of years ago I read the William Manchester/Paul Reid biography of Churchill - "The Last Lion". Volume 1 begins with a superbly written preamble by Manchester of Churchill at the time the movie "Darkest Hour" was set. In the preamble, he gives an overview of Churchill and includes many of his "money quotes". Most of them are on your list and were in the movie. I tend to think the filmmakers/screenwriters of "Darkest Hour" were familiar with Manchester's preamble and resolved to use it as the basis for their screenplay.
This was the first time my wife and I have gone to a movie in two years. My wife has not read much on Churchill and WW2, so it was a good introduction to Churchill for her. We both enjoyed the film.