Interesting link! I wasn't aware of anyone paying for peer review when I was in academia. It appears from the linked examples that it's still rare and relatively small dollar amounts, so indeed not a job.

I love the example of the New England Journal of Medicine finding that paying $5 was worse than not paying, as potential reviewers found it insulting.

As to other activities, yes, I think companies behind journals typically pay people to do administrative functions for the journal, and the editor may or may not be paid (for Nature, I believe the editor is paid). However, it is possible to replicate the traditional review structure in a completely free OA journal with volunteered resources; in computer graphics, I think JCGT does this: http://jcgt.org/about.html