Yes - the shape of the bones in the arms was different than the common foot soldier, along with bone structure in the neck vertebrae and misaligned bones there.
Many were thought to be Welsh and 6 footers as well- considerably taller & huskier than the normal soldier of the day.
Yes - priceless artifacts - of which I'm sure some 40 or 50 were destroyed. Some up to 80" long & VERY large in diameter at the handle to make those draw weights.

The different heads had differing purposes. The blades were to pen with the barbs holding them inside, to disrupt & panic the horses, while the 3 and 4 sided "bodkins" were for armour penetration.

I seem to recall mention of absolute cast as being over 200yards - perhaps around 300yards maximum. Today, the 'lads in the Royal Archer's Society' practice the same type of long range shooting at the butts.

Due to the extremely high ballistic coefficients and sub-sonic launch speeds, arrows slow very little in flight. Their "penetration at range", is surprising.

These arrows pictured are in the 1,500gr. range, seems to me. Today, compound shooters are the rarity who uses 500gr. or heavier arrows.
Fellows hunting with modern glass-backed and bellied longbows and recurves usually shoot from 500gr. to 650gr. arrows. Around here, that is common, with the lighter bows in the 55 to 65 pound range shooting around 500 to 550gr. arrows.