The media is manipulating the story. There's no question of that.
Zimmerman did call 911 more often than the average citizen, but then again he was the neighborhood watch guy. He is supposed to call the police. Of course, that's where his involvement should end-extra eyes and ears are helpful, getting physically involved less so as this case illustrates.
A dispatcher's instructions carry no legal weight in PA and I doubt it's different in FL. I agree that being told the police don't "...need you to do that..." is radically different from, "Do not follow him; pull over and wait for the officer. Do not initiate contact with the male." However, it may be that Martin approached Zimmerman, and things went south from that point.
The police report presents some facts that are consistent with self-defense. They do not make the case completely, but they are suggestive of it. The only way to truly make the determination is with the aid of all available information including witness statements (and there is at least one that states Zimmerman was yelling for help-that's the voice on the tape, not Martin), forensic evidence, and a full cognitive interview with Zimmerman.
Just because Zimmerman was fighting with Martin does not give him the right to shoot him. There must be more than a simple fistfight to justify deadly force. That said, it is not illegal to shoot an unarmed person under certain conditions. Whether those existed is a matter for the homicide investigators and the prosecutor in Florida, not the court of public opinion. I did note that the police report has Martin at 6' and 160 lbs, and Zimmerman at 5'9" with no weight listed. Those are relevant facts. I've also heard Martin was a football player, and if true, that is also relevant.
Martin's dress is relevant, but how much depends on many factors.
Is this homicide justified? I don't know. I wasn't there and I didn't investigate it.
Oh yeah- fuck the Black Panthers.