Steven Winter
Explorer
IMO, it's important for the DM to have a deep and thorough knowledge of the setting. The more the players know, the better, because it brings the setting to life in their imaginations. But asking them to read more than 5-700 words about it at a time is expecting too much. They need to be fed information in small chunks, ideally through in-game exposition. Make your asides about the world crisp, informative, entertaining, and short, and players will know all sorts of things before they catch on that they're being educated.
Steve
Steve