Re: "recording" ≠ "performance"
The simplest solution to the cover thing is to just drop the attribute, which I'd argue gives no useful info at all. But I know most people (or at least a big amount of people) don't agree with me there.
Well, if you ever want to start a petition, you can put my name on it right under ym's :-) I don't know that I'd go as far as "no useful info," but it certainly doesn't provide any info that can't be gotten from a list of recordings ordered by date.
In most cases, it does make it clear which artist originally recorded the work, which is a useful feature. Without it you could still use the work credits but these tend to refer to individuals whom one may not always associate with a particular act.
As I said earlier, I think it's fine to have multiple 'original' or non-cover versions, but most that come after the first are clearly covers. I think it's worth keeping as it's a widely used term, even if not technically perfect.