Tim,
The basics of WP are covered at the WP site itself. You might want to see this article: http://codex.wordpress.org/Template_Hierarchy, which is somewhat techie in nature, but very informative about what each file does. I am sure the WP site is littered with other such documents.
Regarding Suffusion the closest that something comes to being illustrative of different screen components is the graphic at the top of the "Sidebars and Widget Areas" tab in "Suffusion Theme Options". As Mark suggested, you can take a look at things under "Suffusion Theme Options" in general. Though there are many options (around 250, I guess), the tabs on the left side can give you an idea of what can be customized.
Sayontan.
