I came across a couple of other things you might want to add.
When I tried to put an image below the menu in the 3-col fixed layout, the image showed at the top of the column overlapped by the menu. I had to add this:
<div><?php require_once("../CSSMenuWriter/cssmw/menu.php"); ?><div class="clearFloat"></div></div>
To get the image to appear below the menu. The menu extension, I think, should produce a block level element that I can shoose to float or not float. I take it the extension produces a floating menu.
Also, I started with the category of Glow. I noticed that this category has a background image behind the menu (bg.png), but the GUI does not, as far as I could tell, allow me control of the container the menu resides in. That would make it easier to create and control themes.