Currently writing an anti-hero. Points are addressed as follows. (Warning: more in keeping with the '90s comics industry version of an anti-hero than an actual anti-hero.)
1) The character is a soldier. A soldier on the guerrilla side of a war. Civilians and other noncombatants? Well, if they can get under their desk fast enough, well and good, but if they can't see that the people they work for are bastards, well, if he takes an extra quarter second to be sure his bullets will go where he wants them to he might get shot...
An open mind (this goes back to the fact that overtly racist/sexist hero/ines are very rare, even when it would make them fit better within their culture)
Loyalty (But not beyond reason)
Ability to perform the (seemingly) impossible
3) He is damn near superhuman in skill...but there are others like him out there. They're all on the other side. So he has to avoid them or be overwhelmed. Sadly, with the way the world is set up, that is his only limitation.
4) This anti-hero would not exist without the contemporary society. He's not rebelling against the society because he hates it, but because it betrayed him. It's entirely personal and not all that practical. He's out for vengeance, and joins the rebels soely because he figures he'll do better with support than without.
5) Viewpoints a-plenty.
6) Emotionally bereft due to years of training him to not respond to most such stimuli. Emotions seem to consist of boredom, flareups of anger, cold disdain, and, when he's in over his head in a social situation, mild puzzlement.