Your account is exactly right from my understanding except for one thing:
Someone behind you says the attacker is dead.
I believe the female police officer who testified at the trial said Zimmerman did not know Trayvon was dead until she told him later at the police station.
Zimmerman did exactly what I would have done in the same situation. I’m not going to stand by and do nothing if I see a suspected burglar casing my neighborhood.
Thank you for the correction! I have not been able to keep up with every single piece of data on this case. As Winston posted, the caliber of the gun is also significant since it was a one shot lethality. Although, it is penetration to vitals which does the work, so even a .380 would have penetrated at the distance the weapon was fired.