" People can add locations, should they also be able to remove locations?"

Yes, I think that's essential.

" Should people be able to select alternate names for these bookmarks?"

That would be nice...

" How would these be edited?"

But that's likely to be some work.

" Alternatively, should people be able to enter file paths into the dropdown?(It is possible, but not when allowing when naming the bookmarks anything else but a path)"

Typing file paths is always a chore, a selector works best for that.

" Should the bookmarks be saved in the kritarc, or maybe into the Kra?"

Ideally, we'd have a preset-like system like we have for filters, so you can select a set of bookmarks that you can use for more than one image within a project.

Lord, this is UI-hell.

Yes -- that goes for the whole plugin,,,