An English expression for what you're doing is splitting hairs or hair-splitting. All of the sentences are fine. You're right that 5 and 6 have different meanings that depend on the context. But we don't know what the context is.
Your written English is better than most Americans'. (I'm an American.) For what it's worth, you don't need half-quotes around numbers. Only use quotes, half-quotes, and italics when they add meaning.
Keep up the good work!