If you plan on watching Walt and El Grupo I would suggest reading South of The Border with Disney first.
If you've read Disney biographies you know that the story Walt's South American trip is usually over shadowed by the studio strike. Well South of the Border with Disney gives you all the facts about the trip and every South American film the studio made. On to Walt and El Grupo.
Let me start off by saying that I really enjoyed this film. The only reason I suggest reading South of the Border with Disney first is because the movie seemed a little short on facts. Disney's South American trip happened in 1941, since then every member of El Grupo (the artist that went along with him) has passed away. Luckily their spouses and family members have kept all the letters they sent home during the trip.
The film was made by Theodore Thomas the son of legendary animator (and member of El Grupo) Frank Thomas. He did a great job tracking down people that met Walt and El Grupo during their trip. There is not a lot of video footage from the trip shown in the film, instead Thomas found a way to make the still photographs taken at the time come to life. My favorite part of the film is the comparison shots. They will show you a picture of Walt taken in 1941 and slowly fade it to the same location now. It's great to see how the areas have for the most part stayed the same.
Aside from learning more about Walt another reason I wanted to see this film so bad was to learn more about Mary Blair. Mary Blair's section is short but in my opinion one of the most important parts of the film. Mary's son shows us how his mother was influenced by the trip. Before the trip Mary and her husband Lee had almost the exact same style of painting. It was the South American trip that made Mary Blair the artist she became.
So like I said if you're a real Disney nerd I'd say read the book and see the movie. If you are unsure watch the movie first and if you want to know more than read the book.
If you want to see Goofy smoking a cigarette you can watch the original version of Saludos Amigos in the bonus features.