This all really does make quite a lot of sense. The idea of Banu Umayyah deliberately adopting the symbolism of Muhammad and Islam after defeating Ibn Zubair and Hussein fits very well into both what we can gather from the traditional narrative as well as what we might expect to happen from a historical perspective. Zoatar, I'd be curious as to your thoughts regarding Abu Sufyan. Would you consider him to be a historical figure and a contemporary of the "prophet?" Also do you think Hussein's claim of being the grandson of the prophet to have been genuine, made up for his own interests, or invented later on by his supporters?
On your last questions, I don't actually have much of an opinion. Genealogy and chronology are two of the least reliable aspects of Muslim tradition (and Middle Eastern tradition generally). Fictitious genealogies are rampant. Everybody claims descent from everybody, and fictitious ancestors abound.
Not much different nowadays. To take an example I always find funny, an almost unbelievably high number of Americans falsely claim to have a recent Cherokee Indian ancestor. It is almost never any other Indian tribe. *Always* Cherokee.
http://www.dailyyonder.com/cherokee-syndrome/2011/02/08/3170These claims are patently false, but there is some sort of strange reason why they keep getting made. Now, in a climate where there is no ready proof of ancestry, and a great deal of incentive to claim your ancestor was so-and-so, fictitious genealogies sprout up like mushrooms.
So I can't really say much about abu Sufyan except that he may have existed as a warleader back in the day (his name doesn't appear like an artificial epithet), but almost all the traditional Muslim claims about who he was and what he did are likely false (just as with Mo).