While I PERSONALLY agree with most of your hero/villain do's and don'ts I gotta tell ya...you're showing your age on this one Forby.
Those rules really only apply if you're writing for Marvel or DC, and even then they don't apply like they used to. Marvel heroes kill all the damn time now. DC heroes have been getting their hands dirtier too.
Sure, death isn't as permanent as it used to be, but still.
Plus, let's see..the Joker has beaten kids to death with crowbars, blown up their mothers, shot young librariarins through the spine, stripped tham and taken photos to show her dad, mass-executed thousands by lethal gas; Norman Osborn now runs the Avnegers and has them AND his new NEW THunderbolts working as super assassins, Venom/Spidey EATS people...
We've had THE DARK NIGHT RETURNS, THE AUTHORITY, the MARVEL KNIGHTS books, The GL Corps has been given the go ahead for Lethal force.
And yes, the most CERTAINLY DO mention Cap's days as a SOLDIER killing Nazis. Flashback stories, mini-series, the opening to REBORN, and AVENGERS/INVADERS have all shown gun toting Cap and Bucky doing what needed doing. The reason Captain America doesn't kill now is the he no longer works for the armed forces and is not at war. The rules are different, and he has chosen to represent America itself, and not the American Government. He explained this quite clearly during the 80s and 90s when they tried to put him back on active duty, claiming he never finished his service contract due to being frozen in ice. Which, by the way, did NOT happen as a result of him being captured, but from him falling from a plane trying to defuse a bomb in the line of duty. So, yes he IS better than everyone.
And that's just some examples in Big Two land, that's not even touching on books like The Boys, or any of the Avatar Super Hero books! DYNAMITE just wrapped up SUPER ZOMBIES, a mini-series about a zombie plague that gave some people powers but STILL left them as canniablistic, where they ssaved humans only to keep them like cattle on a farm.
Anyway, my point is, that more and more in the big two, and especially in the indies and smaller companies, there is both the room and the opportunity to blur the old fashioned good/evil lines.
I, like you, still prefer my heroes to be "heroes", but at this point that is more of a personal choice than a code of conduct.