Well, I managed to screw it up. :)

I tried changing the height of the navCattabs wrapper to 0, that didn't work, so I changed everything except the width and r/l margins to 0, that made a difference but didn't remove the links. So then I removed the wrapper definition altogether, and it just showed up below the logo instead of over it.

I then removed all references to the navCattabs wrapper, and it went away but the categories showed up in list format in the left column below the logo.

Also, I changed the logo height in header.php (I just copied the default and created /includes/languages/english/red_passion/head.php because the template doesn't come with one), but the size of the main wrapper is still the same. I was then able to shorten the mainwrapper by changing the stylesheet, but when I did so, it misaligned everything.

I'm totally lost when it comes to CSS and php. *sigh* I think I'm gonna have to pay for a designer.