I am also feeling a little unsure where to put what information - I feel like I am being a little redundant in my additional info section since a lot of it is mentioned in my resume and experience sections, but I also don't want to leave it blank. Also, I am not necessarily writing that section as essays, but rather as a list of activities with about a paragraph explaining each one. When I emailed Steven Johnson awhile back he said that clarity is more important than length.
Also, what is everyone putting for "career goals/objectives" in the additional info section? I am not quite sure what to put for that and how specific I need to be. Although I have a general sense what I want to do with my career, I feel like it is too early for me (or most people, for that matter) to know EXACTLY where I want to end up.