I know I'm posting to an old thread, but i'm playing catch up, being new to this forum. I've done a little research on leine, though. (I've made two this year... sort of.)
As for the sleeves, I know that fabric was used practically and economically in early period, hence the narrower sleeves. Later period (1400s - 1600s?), however, wealth was displayed by the amount of fabric draped all over you. Apparently you were much cooler if you had so much wealth that you could waste fabric in that way. Hence the wider sleeves. Also, if you had so much fabric to be impractical to function, it meant you didn't have to work.
Other colors? Oh yes. Brighter colors were preferred, but I know that some colors were only reserved for the head honchos. I can't remember for sure, but I believe red was a reserved color and maybe purple.
Wrap around leine? Hadn't heard of that in my research. Then again, I'm not a research pro or anything. I think your assumption of it being the Eoinar (or however it's spelled) is correct. The jacket-type garment is documented.

~ fionnuala
Do not meddle in the affairs of Dragons, for you are crunchy and taste good with ketchup.