The XC came with very little wiring. Mine had a 1-wire kill switch on the left handlebar. The headlamp on/off switch is mounted inside of the front number plate/headlamp assembly. It is inside where you would never expect to find it in front of the right fork tube, mounted on one of the webs of the number plate (Came new that way). Take a look, yours may be there also. There is no high/low beam switch. Mine was hooked to high beam and that was how I left it.
Killing a bike with the clutch while in gear won't cause any problems but if you lay the bike down and the throttle sticks (or in my case the throttle sticks and you lay the bike down) a kill switch is a good option. Especially if you are still laying underneath the bike
If you need I will look at the wiring and tell you which wire to hook the kill switch to. Just let me know. You can pick up a kill switch for around $10 from any bike shop. I think Sideshow Bob was talking about the multi-function headlight/turn/stop switch for $104
