New Unit: Scots Guard

[The Blind King of Bohemia]

true, but what is importnat here is to judge to what extent "heavily armoured archers" can be. From pictorial sources i've encountered, the heaviest type of armour seen on Archers were transitional armours of the Longbowmen of the Compagne D'Ordannance de Burgundie. Burgundian longbowmen usually wore a mixture of brigadine with mail or transitional armour(if i got that term right. I mean mixture of brigadine and breastplate).

Check out Schilling Chronicles for heavy armoured longbowmen.

The unit itself looks sweet, but i hate the chapel-de-fer warhat being present in late era

The Burgundian Longbowmen were predominately English, so the chance of Welsh and english longbowmen with experience and wealth joining the ranks were very high and being fairly well equipped for war. In the War of the Roses many retainer archers did use some sort of armour. Their job would mainly to be near their lord with the lower archers who were lightly armoured to do much of the killing. The Northern elements, particularly around Macclesfield and Cheshire probably didn't use much armour as their quality in archery aided them enough. Most archers only entered the fray once they had ran out of arrows and the melee was in full sway.

I think the more battle hardened and veteran the archer, the more likely he would be well equipped as the booty and wealth accumilated, especially in war torn france would have been extremely high. If you were part of the archer companies under the Anglo-Gascon armies of Edward Woodstock or the Earl of Derby, who raided into the rich and mostly unguarded parts of southern France then the chance of riches were almost certain.

[Myrddraal]

and also the allaince between France and Scotland can't be break to reflect the Auld Alliance

There won't be any fixed alliances, and thank heavens for that. I want to be able to reforge the world...