I think your theory is off - there is not even a "theoretical" way AM could be a ponzi scheme: the dividends paid out to investors are approximately five times the total investments they received.
The paper value of AM's securities (over 200k shares) are well above the dividends they've paid out. I agree that it is less likely, however.
Yes. But the shares are sold only in secondary markets - when you buy a share, none of that money actually goes to AM (hence it cannot be included in the dividends).