No - Light armor is leather, cloth, etc.
Plate armor is considered heavy armor.
you have to make it yourself
Light. Heavy armor might get in the way and weigh you down. Light is much more attractive of course ;). Heavy armor does offer a lot of benefits though.
The headsman armor has no codes, anything.
i would say it would be light armor not very good but OK and at least a long bow and steel sword the armor should probebly be at least stormcloak 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.
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.
The Necklace of the Peerless Squire is an enchanted necklace and can be made by enchanting a necklace (any sort) with Fortify Light Armor enchant. However, for the Peerless Squire, you'll need to max your enchanting level. Peerless Squire will increase Light Armor skill by 25.
It is daedric armour!
Well if you are referring to the armor I know it just powers up your current thieves guild armor (one piece of it) to make it stronger. If you are talking about the trainers they have in the thieves' guild I know there is archery, lock-picking, and sneak. I am also pretty sure they have pick-pocketing and light armor.