I don't know Florida law. But it was problematically short on information by the standards that I'm a familiar with. As ballen has noted, all it really establishes is that Zimmerman shot Martin, and that Martin died as a result of being shot. The rest is unsupported statements and conjecture. For example, when did Zimmerman make those statements? During the 911 call? At a subsequent interview? How do the Affiants know what motivated Zimmerman? If, for example, he stated in an interview "I believed he was a criminal." -- why not say exactly that?
I don't know Florida law either, but the Affidavit--to me--establishes more than just A shot B dead. It establishes that:
>Martin was lawfully in a place where he had business to be (he was living in the neighborhood);
>that Zimmerman also lived in the neighborhood;
>that Zimmerman observed Martin and deemed him to be suspicious;
>that Zimmerman was asked by a dispatcher not to follow Martin;
>that Zimmerman was advised that an officer was en route;
>that Zimmerman made disparaging references to people other than Martin (i.e., "these azzholes, they always get away")
>that Martin was on the phone while walking (again, in his own neighborhood)
>that Martin's mother did listen to the 911 recording and identified her son's voice as yelling for help;
>that a struggle between Zimmerman and Martin ensued; and
>that Zimmerman shot Martin and Martin died.
Strong and very reasonable inferences can be drawn from each of the points I just listed, without documents or testimony needed to support each point. Not big kangaroo leaps of inference, but the kind of inference that supports the notion that Martin was in a place where he had a right to be and that he was likely heading home.