uhm..hmm
Just a thought here, can it be that Vader has a shorter battle helmet? one that does not impede way of arm movement?
When it comes to the miniskirt / thermal wear, as a Cyborg it looks like he can feel pain ( when Luke swings at him with his saber on Bespin he says: Aarrh!!, or something ) and he does have fleshy parts...why would he not want them warm, limber and cozy..instead of frozen ?
but as always Adywan manages the impossible and thats mein herren is COOL !