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...each of which has a unique orbit. :') Also, there are more to be discovered, and eventually this "Buffy" oddball could be known as just the first of a whole family of similar objects. That has definitely happened before.

That's certainly possible -- which is why they say its discovery raises questions about the origin of the solar system. As current theory has it, the solar system originated from a spinning ball of gas, which is why everything we know about is pretty close to the ecliptic. To find a bunch of bodies in near-circular, off-ecliptic orbits would suggest some other mechanism.

I say "near-circular" for a reason: highly elliptical bodies would be in orbits that should take them close enough to us for easy observation, and we'd probably already know about them.