Interesting questions Colin
as a rule for f-fly type flies and buzzers I use the tips as you do, vary the quantity to suit the hook
16=3, 14= 4, 12= 5 and the like. I only ever use natural CDC it floats way better than dyed stuff
and I have never found a need for colour matching. Only time I use dyed CDC is for the CDC spiders when I spin the fibres in a dubbing loop but I use these because they stick in the surface or sink slowly.
Hook weight has a bearing on this too. With CDC I use light hooks like TMC 103 or partridge sld's
if I need heavier hooks then I tend to use snowshoe hare instead of cdc
twisting a CDC feather into a rope makes a good body too and can help to keep a dry
on the surface but I like my flies in the surface so mix it with very fine wire, makes it tough too.
It's good stuff, but I'd stick to natural colours if you want it to float,
it's worth paying for good stuff too, bennechi or petitjean
hope that helps
sandy