For a longbow with it's (presumably, I actully don't know) longer arrows placing them in the dirt at your feet would be quicker than using a quiver. However this would only apply to set peice battles and prepared ambushes. The Normans were using compound bow at hastings and the bayeaux tapestry shows them putting their arrows in the dirt.
I believe the first mention of the Welsh longbow is from the Peterbough Chronicle. The Norman's were mentioning the bows of the Welsh as something special upon they're very first encounters with it. I think I read once that most bows could penetrate mail at 30 feet the Welsh/English longbow could perice mail at 50 feet.
I've only ever heard the claim that pathologists can identify English longbowmen because of their bones. I've never heard this stated about any other archers anywhere any time. The draw on those things must have been huge.
As for horse archers and arrow storms. Oh yes they did! That was the point! Imagine two thousand horse archers charging you, rank upon rank of them, and firing arrows as they charged. The arrows fired from further away coming in at high angles while arrows fired from closer at lower angles impacting at near the same time. At about thirty feet from your line they suddenly wheel away carrocle style performing the parthian shot as they ride away. Once safely away from you the horse archers would reload their quivers and do it agian and again and again. When you couldn't take it anymore, to busy hiding behind your shield and not expecting it, they'd not wheel away. Whipping out their sabres at the last instant and charge home. Also horse archers could ride around your shield wall on the flanks pouring fire into your formations ala old holywood westerns with the indians riding in circles around the wagonberg.
The magyars smashed numerically superior armies again and again using this, only to have the mongols return the favor a few centuries on.
I've seen a Magyar composite bow. It was truly a work of art. The waterproofing was snakeskin.
I'll write my opinions on crossbows tomorrow night. Someone started a thread on pikes and I definately have to get in on that
