Personally this is a case of STUPID!
I agree with your assessment. Lots of stupidity here.
As you said, Zimmerman should have stayed put. He wasn't qualified or competent to confront someone, either verbally or physically, and he was advised to stand down by the 911 operator. Regardless of anything that occurred thereafter, these factors, alone, were enough to convict for manslaughter, even with the "Stand Your Ground" law in place.
Unfortunately, the prosecution overreached. I don't know how they ever thought they could get a 2nd degree murder conviction -- perhaps they acted under pressure? But, given this, they were almost doomed to fail.
The race issue is very tricky. For those who are not themselves minorities, it seems silly when both individuals involved in the incident are part of minority groups. However, this assumes that all minority groups get along with one another -- which they don't. Hispanics and African-Americans have a history of dislike and/or distrust of one another, in some parts of the US. Even touchier is the issue of "light" vs. "dark" skin, since Zimmerman apparently is partly of Afro-Peruvian descent. Thus, if you identify as "African-American", it simply looks to some like a case of "not again".
I don't think the entire African-American community feels this way. In fact, not even the majority. Many believe that Zimmerman should have been convicted, but don't believe that race had much to do with the shooting or the trial verdict. As Albatross and others said, the media has done its part in blowing this aspect of the case way out of proportion.
As for Trayvon Martin, I don't think anyone has claimed he was a saint. However, if an un-uniformed stranger with a gun and no badge confronts you, how would you react? And if Martin *had* grabbed the gun and killed Zimmerman, would he not have, himself, had grounds to claim self-defense? (This, of course, depends on who confronted who first.) Such cases are never simple. And sadly, because dead men tell no tales, the benefit of the doubt automatically favors the survivor.