When Koko says she's selling arms to aid the cause of world peace, though hypocritical, she is being completely truthful. After all, even if you've got a friend (and some people you've kidnapped) doing the hard work building a quantum computer and then miniaturising it down to a 10 feet box from the size of a multistory building would require an astronomical amount of money which she has raised through her illicit arms deals.
Pretty much everyone in the series is Combat Pragmatist and many are active military or paramilitary (Night Nine and Hex's team) personnel or are retired from the same. A common attitude in the military can be summed up thusly: If you are in a fair fight you've done something badly wrong.
When meeting Bookman at Dulles Airport, Koko tells her team that lunch is on Bookman, who has an Oh, Crap! reaction and figures that lunch is going to cost him US$2000 dollars. A normal mealset at a Five Guys burger joint (which is the place in question) will cost about US$10-12, so a rough estimate would be that a meal for ten people (Koko & crew makes 9, plus Hinoki makes 10) would cost between US$120-200. There are thus two questions:
How much did they eat?
How much did Bookman eat?
You should go to the food court at an airport terminal once you get past the security check point. The mark up in any of the shops once you are at the terminal gates where you board a plane is anywhere from 50% - 200% sometimes more depending on what airport you are in. They are able to do this because they know once you are there you have no other choice besides leaving the airport to get food or anything else.
Quite interesting that Koko and Wiley can't enter American soil considering that they're under a FBI blacklist. But since they're in an airport...
My guess this would be where their numerous fake passports would come into play. I think it was her brother that bragged about how many fake identities and passports he had earlier in the series. It would be a safe assumption that she and her crew had them also.
In the anime, Chinatsu was originally a normal girl who was in an opera house with her parents when he slaughtered the entire cast and audience except her (by accidental survival, not his choice). How she went from her rage and an attempt to kill him during that to her killing skills and psychopathic devotion to him is best not dwelled upon.
Hex tried to capture Jonah ALIVE. Koko probably realised this, what Hex had been trying to do and how close she came to succeeding when Jonah actually got drugged and couldn't even defend himself. So maybe Koko's explosive response doesn't seem all that extreme anymore.