Alan,

those web links helped me a great deal when I first started researching this. Just as the "saffron" leine was worn in both Ireland and Scotland, so too was the colour almost universally described as being a bright or mustardy yellow.

The dye Pearse used is something called 'cottle", although I haven't a clue what it is other than a plant.

There's a shared culture here, so could not there have been (say, on the Aran Islands) a Scottish influence (this doesn't have anything to do with plantations, Orangemen, or Ulster Scots/Scots Irish) in the wearing of the kilt and the playing of the pipes?
Certainly possible. Just remember, the pipes didn't come to Ireland through Scotland, but the other way around.