Light Metering ?

haha. I'm not even sure if what I'm asking makes sense but I'll give it a go.

Are light measurements taken through the lense? For example, if I'm half-pressing my shutter on Auto and it gives me the exposure settings, is that information being collected through the lens?

If so, would the type of glass play a role in determining correct/more accurate exposure? (kit lens vs 17-40L)?

I'm not so much talking about IQ, but rather a camera's ability to determine accurate exposure settings because of the lens.

Am I making any sense?

Yes, the metering's done through the lens. And no, the quality of the lens won't make a lot of difference in how well the camera can meter. The metering cells are in the pentaprism and reading off the focusing screen, so they'll (sort of) be affected by maximum aperture (the camera will be able to get a meter reading in darker conditions with a faster lens), but the resolution/aberrations aren't going to have any particular effect.