Without~Worth!
I have answers to both questions!!!
1) How did Karou scare Kyo?
All the members of Diru were afraid of Kaoru when they had first met him. Apparently, he was a very intimidating person at first, which is true. Look at the man, try meeting him and finsing out you'll be working with this guy for who knows how long now...I would be a little afraid too, if I didn't know how goofy he can get.
2) Why does Kyo's chest always look sratched up?
It's all part of the fan serivce heart . Even though Diru don't molest each other any more, as they used to, Kyo still gives us girls some reasons so get all giddy, like his dancing, how he hicthes his pants down JUST enough to tease us, or, for us 'freaks' who love to gory stuff, he cuts his chest up. Just as he vomits blood and stuff, Kyo will, at one point of the show, take a saftey pin ((I belive this is what he used at the NY show)), and carve something into his chest. He's been doing it for sometime now, so I'm sure there's probably scars. I forget exactly what it says, but I know it's backwards... I'll see if I can find the page which tells what it said again somewhere on LJ <3.
Kyo scratching himself up and hitting himself in the chest/head is also just a visual addition to the show.
I think that should cover all your questions ^^.