If you want to know about the dark underside of Hollywood, one place to start is
Assistant/Atlas, who's a young guy working as an assistant in LA. For example, in
this recent post he discusses the various kinds of assistants you can be when you get off the turnip truck in Hollywood. (As personified by members of the cast of
Entourage, but that's because he has too much time on his hands.) Particularly interesting are the first four months or so of archives, when he's working for an evil boss. While his writing is acidly clever, it is also illuminating to know what kind of short-tempered greedy maniacs your scripts are going to
if you're lucky.
I reiterate my theory that the best first job for a screenwriter is agent's assistant... (though technically to get to be an agent's assistant you have to slave in the mailroom for a time determined primarily by your ability to connive your way out of it).