For the life of me I can't remember when that "trauma" had any negative impact in his actions. I could be mistaken - I don't remember it at all.
There was a whole subplot for the next book about how Harry is now afraid to conjure fire, and because of this effectively cannot. He does get over it, but not easily.
1: Token flaws, mostly. What is his fatal flaw? How does that affect him negatively in a serious way?
He's impulsive, emotional, a sucker for a lady with teary eyes, and generally pretty easy to manipulate if you understand him. He, again, starts a war that nearly gets him killed several times, nearly gets his loved ones killed several times, and does kill several teenagers for whom he had assumed responsibility. He was set up to be coined by Nicodemus, who again in the book I'm on manipulated him into calling the Archive to mediate their dispute specifically so the Denarians could hit the Archive. Elaine played him like a fiddle in Summer Knight. He was manipulated into assaulting Arctis Tor, and we haven't seen all the bad news coming his way from that.
3: Why don't they? He makes a lot of enemies yet not one single sniper shot to the head?
Mab and Nicodemus see him as a resource and recruit, not a rival. The Merlin isn't going to just throw down with him in a magical brawl. Lara Raith and Marcone try and keep their people out of Harry's way, and he is sometimes useful to them. The vamps, AFAIK has never tried a sniper. But they have tried multiple ambushes by gunmen, a car bomb, a duel to the death, a massive ghoul strike force, and on one memorable occasion, delivery of a claymore pizza.
Kincaid points out (and in his head, Harry agrees) that a sniper rifle is a fine way to take out a wizard so quickly he can't even get off a death-spell. Why it's not more commonly used, I can't say.
2: WHY DIDN'T THEY? I saw no good reason for refusing to comply with the red court demands, nor how could harry, outcast, would get enough support not to get dispatched.
Because by vote in that same meeting Ebenezer McCoy was elevated to the Senior Council, and he lobbied long and hard to get Ancient Mai and Injun Joe on Harry's side?
Up to the point I read, he remained at large. Other than the duel, I remeber no attemps on his life in a serious capacity, nor he fighting said war. If he did fight, good for him, Butcher at least improved.... sadly past the point anyone should care.
There's a bit of Summer Knight where Harry describes some of the attempts made so far, and his growing paranoia of leaving his warded home. In Dead Beat Harry gets sort of drafted into the Wardens, because the war took a serious bad turn and there are now less a dozen in North America. In fact, he becomes one of four Warden Commanders in the US. After this there is much discussion of his fighting, after the events of White Night he helps set up a network of minor practioners to gang up on threats or pass along information, the Paranet.
But he really gets serious about the thing after the Battle of Camp Kaboom, where Harry and Ramirez were training young recruits in battle magic, they were ambushed by that large strike force of ghouls who carry off and devour alive several of Harry's students.
Harry's reflexes and instincts have clearly sharpened as a result of years of conflict with entities whose preferred anti-Wizard tactic is ambush.
