use custom menus as simple overlays of header image?

I'm trying to do two things that I think should be reasonably easy to do, and as a not-great coder, I don't want to get too far into screwing around with css.php or other theme files before I ask around (I have been searching for a while on here for some solutions).

The site I'm working on is http://www.ichingstargarden.com.

The FIRST item, to address in this forum, is as stated in the subject: I want menus overlaying the header image that are laid out vertically - see the attached export of a sketch to get the general idea of what I'm going for. In case it's too small to make sense of, I envision blog categories stacked up at left top, and pages stacked up at right bottom. Or vice-versa. But basically this type of layout - and just text links, not buttons (though I might like to style transparencies - but that, I could handle).

Anyone got ideas? I would rather NOT make buttons to overlay (which I can), I'd rather have these be governed by the custom menus function. I feel like I may be missing a large and obvious piece...