tomh,
you are correct in what you have decipered of the CSS. One thing to note is there is a difference between margin and padding:
http://blog.webassist.com/2010/01/th...s-and-padding/
which seems to really only matter if you use borders. However the margin and padding added together is the whitespace you will see around your text.
The hardest part seems to be getting the settings to apply correctly. Because if a particular font is appled in the "p" (paragraph) block then if will take priority over what you set in the "html" or "body" block. And then you can have classes for the elements and that adds a whole new dimension.