it's okay, us geeks'll do it for ya.
You're pretty much right on. I just checked, it's about 35kg of plutonium oxide crystals or 13kg of plutonium metal for a sphere size of 18cm and 12cm respectively. I don't know how much HE it takes to get the sphere supercritical, but still thats a pretty small package.
Wolf, I had heard about the movie for some time but couldn't find it anywhere. Now you can order it from Amazon or download it from the net. Narrated by William Shatner. There's another good one called 'Broken Arrows - Nuclear 911' narrated by Leonard Nimoy.