I don't know about Hawk, but personally when I'm making something for purely online viewing (ie for the comic I'm working on making) - I feel like I'm cheating with my method.
My original image is much as you describe (and nothing like the look of the hawk cam work
) - where in it has those smudges, stray 'thought lines', etc. - for web viewing I pull out a sheet of tracing paper, and a good micron pen - and ink the tracing paper then scan that (get good white tracing paper - and put a sheet of white paper behind it, and it's actually cleaner than ink on the white paper itself) - and it turns out quite clean (if you need an example, my character sketches are in my deviantart gallery heh).
My thoughts on how Hawk's images are probably so clean: The angle his work surface is at aids in his sketches being 'clean' - as it keeps his hand from resting/dragging on the image. Some people love drawing that way (and if you want the original to be very professional looking - its almost required unless you use the cheats to get a clean looking image) - I personally can't draw that way, doesn't feel natural to me.
As for mechanical vs wood - both have their advantages, I tend to use mechanical almost strictly as it's what I'm used to, and it's good for hard lines - where wood pencils have the advantage of being able to do smooth pencil shading better (by using the side of the pencil) - it's more difficult for mechanical to do this (you have to be very experienced using them).
Wood pencils can be overall more useful, if you keep them sharp (sharpening almost insanely frequently) - but if you're not anal about sharpening after every few marks, they're about equal as far as usefulness.
---end of my 2 cents---