I was originally intending to go with smooth nodes for those, but after making some comparisons, I decided that sharp ones look better. That fuzziness seemed like a funny little detail so I included it too, heh. Thank you for your opinions though.
Not really. This is the only drawing that really caught my eye; the others were nice too, but I found this one to be particularly awesome.
Um... no colour guides, I just went through various Spitfire deviations and picked up what I thought looked the best, additionally editing colours whenever I saw it fit. I wanted to take colours from the Hurricane Fluttershy iTunes episode I have, but they looks so washed out on her that I went looking for other sources. Editing things whenever I see it fit - that's how I work.