How does one go about killing a Transformer?

I wonder if there is some reason why some Transformers have their sparks externally located. Obviously, Energon Transformers can protect their sparks using Energon Stars, but why do the Transmetal 2's and BMs have external sparks - isn't this just a massive vulnerability?

 

Also, as per BW it's possible to alter the allegiance of a spark by chipping it to the desired faction. Presumably, some sparks have a basic 'polarity' to either Con or Bot.

I assume you mean the orange, yellow, purple crystal things on the toys? Right? Well if that's so...I'd chalk this up to toy-gimmick-thing. I wouldn't think too hard on it, if I were you, but if you can come up with an awesome explaination...well that'd be cool.

If you look at BW TM2 Cheetor's Spark was in his leg. But the spark itself was hidden underneathe his exo-structure and other components in the BW show, so it was protected as much as other vital parts.

And with Energon...I don't remember ever hearing their Energon ports were their Lasercores/Sparks. And if you follow the show that doesn't seem to be the case. Kinda neat if it is, but very vulnerable spot to have like that.