I haven't actually done much fighting in camp, but that doesn't mean it won't come up. So, Roxas' fighty meme.
Abilities?: River is a super-fighty godmoder. She's a ridiculous crack shot (she can headshot with her eyes closed after spending less than five seconds determining target location), and she can kill piles and piles of fighty-types without breaking a sweat. Literally. She can fight with or without weapons. May or may not be able to read minds to anticipate actions. For a human, she's a top-tier fighter.
Canon?: High. Very, very high. River was made to be an assassin, she's really good at it. Mal called her a 'demigod' in her meme, and that's probably not too far off. River is barely scratched and not even breathing hard after a fight that has most of the crew severely wounded.
Camp?: Moderate-to-High. It's hard to judge that because so many people have speshul powers and we don't ever get to see the scope of what River can actually do. People with superstrength and supermagic could obviously pwn her, but humans and other trained killers? I'd estimate that River would probably beat most of them, unless they're augmented too.
Psychic?: She is one, and her brain is a very confused and unpleasant place.
Permissions?: River saves (I think she's the only Firefly cast member that does) and views death pretty nonchalantly. If and only if no one else is around and she would not be found out, killing River may be okay. It NEEDS to be planned out in advance, and will really only be okay in very certain and specific situations. Minor injuries are okay, but I'd prefer River not get maimed because her solution to that would be to kill herself and reset, which, if Simon knows about it, will cause emo. Please don't make Simon emo more. Seriously. No one wants that.
Abilities?: Kaylee is a completely normal and average human being. She is capable of shooting a gun with moderate-to-good accuracy, and she might be able to lob a wrench at your head. That's about the scope of it. She tends to panic when attacked.
Canon?: Loooooow. We only see Kaylee get over her fear and fight once in the entire canon, and that's with the potential promise of sex with Simon. Obviously she requires motivation.
Camp?: Looooooooow. Lower than canon, even. Kaylee would ATTEMPT to protect herself or her cabinmates if attacked, but she'd suck pretty hard at it.
Psychic?: Kaylee has no psychic powers and there's not much interesting a psychic could get from her besides sexy images of Simon, and lots of mechanical and computer geekery.
Permissions?: Kaylee is absolutely not for killing. She doesn't save, and...she's Kaylee. Just please don't. Same for maiming. Unless it's something specifically planned out and most likely initiated by me, I don't really want her disfigured or disabled. Injuries of the non-fatal sort are okay as long as we talk about it first and she's in a situation where it makes sense. No drive-by shooting, but if she's in a combat situation, it's okay.