*easier access to and use of artwork sizes, both dimensions and storage space
I guess you mean showing it in the main panel as a field. I have been looking at this, and i dont think i can implement it without negatively impacting performance vs. how many people would actually use it. What i could do is add it as a field in the files to edit filter for artwork, so that information only shows in that dedicated panel. It would still be slow like the small artwork filter, although i could make some improvements to that so it caches the data so its slow only the first time. I can probably also include this in the new files to edit panel:
*ability to quickly see if all tracks from the same album have the same artwork (not just similar images, but actually the same)
I'm open to other ideas, but that sounds reasonable.
*ability to see all artwork attached to a file in the main panel, or at the very least the number of images (for instance, a small number overlay that could be displayed on the artwork shown)
could you explain some more how you think those might work
Obviously the main panel thing would depend on the view. It wouldn't be possible to do in the main panel in Tracks view, but maybe the artwork panel could show how many artwork files are attached to selected tracks (I'd think just for a single album at a time or it would be too hard to calculate). Then you could click on the number to open something like a tag inspector for artwork, a window similar to the Google search window that showed all the different artwork in a grid and would allow it to be deleted or attached to all files, etc.
In Artwork view, I think there's already been a suggestion for showing all the artwork for an album across the top of the expanded panel. I think you could still find a way to incorporate the artwork tag inspector as above.
In Album & Tracks view, maybe the artwork in the main panel could work like tracks view, but if info is displayed to the right of the artwork, then there would be an arrow or something you could press to show all the artwork for that album down the left side of the panel.
*some better tool for editing multiple artworks than the current tag editor panel
This would be the "artwork tag inspector". I figure artwork would be shown in a grid, rather than a column, ideally with file info on each piece visible, too. You could delete an image or add it to all tracks the same way as tags in the tag inspector, and reorder them however you wanted. I think this should come up automatically when you paste artwork onto a track or tracks with multiple images, so that you can decide whether to replace an existing image or add a new one (maybe you could optionally disable that, if you didn't care about multiple artworks).
That's just what I'm thinking off the top of my head. I don't have the how set in stone.