What youve said confused the shit out of me mate Heres how I understand it.. how far off base am I?
Kelvin is a measure of heat - think of it as degrees celcius if it helps. Now, when you heat up a piece of metal, it first goes red hot - if you can keep heating it then it starts going yellow, heat it even more then white hot.
Candles is a measure of how BRIGHT something appears, in a darkened room, you light 1 candle - and you'll illuminate the room to a certain extent. Light a 2nd candle, and the amount of illumination increases.
So, the rating of 8000kelvin for a set of headlights is the equivilent to how HOT it is getting which determines the colour (5000, yellow hot, 8000 white hot)
A rating of 1000 Candles for a light is a comparison to how many candles would need to be light the same amount of area.
SO, you can have 5000kelvin 1000 Candle and youd have a yellow light.. or you can have 8000kelvin 1000 candle and itd be quite a white light. Both would illuminate the same amount.