I had a problem with finding the admin page for imagecache 2.0 as well. Eventually I emptied my cache_menu table. I want to remind you that Ubercart hasn't been updated for imagecache 2.0, so there's probably some problems with the way it automatically adds presets. Once they are set up right, though, I expect the pictures to show up.

Last I checked, Thickbox hadn't been updated for IC 2.0 either. Has that happened already?