Was Darren Wilson justified in killing Brown? Legally Yes, Morally no. The evidence for the case is available online. As soon as you lay hands on a officer you are willing to face the consequences. The evidence also suggests that Brown was an aggressor. It did indeed show that Brown had approached Wilson after shots were fired. Approaching an officer after repeated warnings/confrontation is grounds for self defense by law. I personally blame the witnesses for having such radically mixed accounts for what happened. Clearly some were lying in Brown's favor and may have ruined the people who spoke the truth. That being said, I do not think Wilson needed to shoot, nor do I like that the police force always falls back to "this is how they are trained," It's like they can't think for themselves in these situations. It's a matter of overreacting and power delusion.
As for the Jury, no it did not matter how many whites were on the jury or how many men where there. The decision was unanimous. Don't fucking generalize people.
As for the "peaceful" riots, as NBC put it, "people asked, 'why such a large police presence?' Well here's your answer."
There will always be people that incite looting and destruction when it comes to this and for the most part they use the situation as an excuse for it.