Half of the issues you raise here is more about interpolation than about quoting. The document is about quoting, and so IMHO it should keep itself to quote matters. Some aren't directly about quoting, and some aren't directly about interpolation.
Perhaps one can do a sister document that is about quote interpretation that would include both interpolation issues and and escaping issues, and link between it and this document.
See perltoc if you don't know which perldoc to read!
Read argumentation in its context!