The headsman armor has no codes, anything.
No - Light armor is leather, cloth, etc. Plate armor is considered heavy armor.
There is no Dragon Priest Armor, only their masks.
Armor points refer to how effective the armor is against preventing damage, the higher the number, the better.
you have to make it yourself
There is a mod for skyrim which allows you to give your horse armour (it makes your horse practically invincible btw), but without the mod installed, horses can't wear armour.
No, the actual look of your armor has no affect on stealth. However, the weight of it does.(the lighter the better)
There are Falmer helms, torso armour, shields, and weapons.
there is a way if you boost all of your skills over 100 and then disenchant it
It is daedric armour!
Random Items, Daedric artifacts, Daedric sword with full blacksmith+ armor with blacksmith on it, then enchanted with armor with + enchanting
There is no "back" armor in skyrim. However some armors will include a cape, such as the Nightingale armor. There is also a mod on the skyrim nexus called "cloaks of Skyrim" that will allow your character to wear a cloak or cape.