Hi Dan,
As Mary has said, the large icon type images are simply that, images in the topic section of a page with hyperlinks. Having seen it here first, I used it for my original primary school website as the children (and some of the staff!) prefered it to navigating menus.
The custom menu option for Moodle 2 is a really useful tool to create menus without needing to go into the theme files themselves as you needed to do in Moodle1.9. It can be difficult to style, but if you find a theme you like as a starting point and explore how the menu is styled there, and then look at a few others, you can eventually find your way around it. The other thing with the Moodle2 custom menu is once you do get some experience playing round with the Moodle Themes, you can look at overriding the renderer to do all sorts of things with it.
Maybe one step at a time, but keep on going - the moodle learning curve gets you there and with the support of the 2 Marys and others on these forums, everything is achievable!!!
Rich