It doesn't cause the phases of the moon, only a lunar eclipse. This makes its orbit fairly difficult to predict.
So what causes the phases of the Moon? Eclipses are easy to predict, so it should be easy to chart the course of the body that creates them.
Perhaps it is made of living material, or - more likely - it picks up matter from somewhere else, perhaps the solar wind.
I would stay away from the living shadow body model if I were you.
If it is picking up material from the Sun, this would make it difficult to remain the black body required for no observation.
It can't be significantly smaller than the Sun and Moon, or it would never be able to cast a shadow on the full Moon.
What about Tom's flashlight explanation (the shadow puppet on the wall one)? If the shadow body was of significant size, say planetary, cometary or asteroid, it would be visible like those other bodies.
I'm afraid I don't follow you. Why would it do that?
Sunspots grow larger and smaller variably. In order for the changing size to be accounted for by perspective, that would mean the debris is moving up and down.
No, but as pieces break off they are struck by particles in the solar wind, which will give some of them a net charge.
This doesn't explain the orbit of the debris. The debris is in an orbit that is determined by the orbit of the shadow body. The solar wind would energize it, but this would be a gradual process, and the path of the debris would be continually changing. It wouldn't just "poof" into an orbit and then stay there.