I was careful to write "light" text, but I wasn't careful enough to write "write" instead of "right"! And sorry, I shouldn't have written "glare": I found it refers to reflected light while I was thinking of emitted light.
a) "does this come from a scientific source?" Does it have to? What hurts your eyes more, staring at bright sources of light or at dark sources? Why do you wear sun glasses?
Check the graph here:
Then try working 10 hours a day with predominantly white files or webpages and 10 hours a day with predominantly black files or webpages and tell me if you'll feel a difference.
b) Of course you can "move on from one attachment page to the next". All themes have previous/next navigation links or thumbnails (you might be interested in that) on att. pages, and some of them (including the one you're using) jump to the next att. page when you click on the image itself. See here:
c) You got me totally confused re image size, image quality, and att. page vs carousel view. Are you looking for best quality or not? Do you mean att. pages give you larger images than the carousel does or not? I checked one gallery page of yours, and the files are 450px wide so first they're not detailed enough, second carousel and att. page should give you exactly the same size and quality. Do you have other gallery pages with larger files? If so, link to such a page please. Also, what's your screen resolution?
By the way, why don't you link your username to your blog?