asterion, you bring up several points of copyright law that I don’t know. I’d be interested in knowing myself. However, these are mostly interesting possibilities to unravel in the law. The core problem isn’t people recording themselves singing someone else’s song. The core problem is blantently taking a copy of someone elses work for the express purpose of not having to pay for it.
All except your first question, which is pretty straight forward. If you’ve paid for the property, then you’re allowed to own it in the form you choose. And that means taping your CD is ok, ripping it is ok, and downloading another copy of it is ok. You paid for it; you own it. (you can’t distribute it of course, but that wasn’t the issue)
The issue is people who choose to download it and not pay for it.