CSS class for styling individual image-attach nodes

Well technically you could grab those on:

div.all-attached-images div {}

Also, on nodes we get image-attach-body/teaser. If we add a class image-attach-node then that's perhaps overkill. Logically the body/teaser distinction should be on the wrapping DIV.

Looking at the theme function classes again, I think they're right as they are.

When there are several images, they have a wrapper; when there's just one image, it's alone. We could make the class on the multiple images just image-attach-node rather than image-attach-body, but I like the body/teaser distinction we have there -- it feels more consistent.

As for your original problem, you can grab on the selector I mentioned.

Closing as won't fix.