Reasonable question!
I don't think the overall shape of the pipe is too important other than aesthetics; say Billard vs Canadian vs Bulldog etc.. The length of the stem can cool the smoke, but I think most Canadians are too short to make a difference compared to e.g. Churchwardens. The internal bowl diameter and height, I believe, makes more of a difference. I prefer to smoke va's and vaper's in narrow tall bowls, English and aro's in the medium wide and wide bowls.
Regarding the stain/unfinished stain I have no clue...