I wish I spoke German

«I write differently from the way I speak, I speak differently from the way I think, I think differently from the way I should think - and so it goes on into the darkest depths of infinity»
(Letter to Ottla, July 10, 1914)

The Kafka Project seems like an excellent site for research, especially if you speak/read German. Kafka's manuscript on The Trial would be a great place to observe the insight of an author and the choices an author makes when writing.