There is a much more modern thread on tactics for this, so I am closing this one, as most of the above dates back to when Scrivener barely even had what we’d now think of as document bookmarks, let alone a tool that allows for rapid navigation between unique pieces of text (search for “Quick Search” in that thread, which sounds quite a bit like point (2) in the list above).
What would be even more unwieldy and unfeasible would be to create a separate note for each one of the hundreds and hundreds of quotations (as has sometimes been suggested to enable direct-linking to individual sources).
I understand this can be a matter of taste, to some degree, but do know that is how Scrivener was designed to be used. It was not designed to accumulate large amounts of loosely related data into single outliner nodes like you describe—particularly with Scrivenings mode around which makes the notion of them being “split up” to be a nearly artificial concept.
But like I say, any further discussion should be carried over into the context of the more modern framework, rather than one from over a decade ago.