There's nothing that explains Brown turning around unless he was being shot at.
Of course there is. Wilson gave chase and repeatedly told Brown to stop. Having just been shot in the thumb, he probably thought he might be shot in the back if he continued running. So he stopped and turned to face Wilson, perhaps with the intention of surrendering (consistent with witness 104, who said that he looked like he was raising his hands for a moment), but then his anger or his pride got the best of him and he decided to make another wreckless decision, one that would cost him his life.
I can't see anything about the scenario of Brown charging at Wilson makes any sense.
But that's what the only credible witnesses say happened, and it's consistent with the distance at which Brown traveled back to Wilson (20ft). Taken together, there should be no doubt that Brown charged Wilson, whether in a rage or in self-defense. The other witnesses you're relying on were not discredited based on "nit picks" (really?). They told outrageous lies that were intended to paint Wilson in the worst light, and several of them were forced to admit that they lied after forensics exposed their accounts as bunk. Indeed, one of these "pro-Brown" witnesses flipped and corroborated part of Wilson's account, stating, "it appeared that his life was in danger", referring to Wilson. Here's what the DOJ had to say about her
"However, her reasons for being untruthful, coupled with the fact that she immediately changed course when her statements were challenged, give her account reliability. "
You also ignore the fact that Brown was high on drugs at the time, which affects judgement. This can be observed in his behavior at the supermarket where Brown perpetrated a strong armed robbery without any attempt to conceal his identity. He acted entitled and fearless, as if the laws didn't apply to him. Dorian Johnson, in his grand jury testimony, was stunned by this wreckless behavior and immediately put back the stolen cigars that Brown had handed him (this is seen on video). So the evidence establishes that Brown was high and that he engaged in very wreckless behavior just minutes prior to his encounter with Wilson, and here you are saying it's "ludicrous" for Brown to engage in more wreckless behavior during this confrontation.
Further, Wilson claimed that Brown said, "you're too much of a pussy to shoot me". We know from people who knew him that Brown was accustomed to using his great size to intimidate people, as he did to that clerk at the supermarket. Perhaps he thought he could intimidate a cop with a gun too -- banking on his great size to send Wilson cowering.
As for the arm wounds, from the DOJ report
"However, the concentration of bullet wounds on Brown’s right side is consistent with Wilson’s description that he focused on Brown’s right arm while shooting."
All bullets hit the right side, including the two ambiguous arm shots. That strongly indicates that all hit while Brown was facing Wilson.