Re: Thanos' bare hand
Thanos was born an (in)human. There's comics that show Thanos as a child with his brother Eros, and both are just as "normal" looking and white as yer average garden-variety Caucasian. It's only when the Deviant gene started setting in that Thanos started changing, while Eros (Starfox) remained "normal" on the evolutionary charts.
But yeah, the camera's focus on the hand is definitely intentional. That's Thanos' Gauntlet hand, and Joss is pointing out that the Mad Titan is not wearing it. Yet.
THE COTTON AVENGERS
...They move like slick cotton on oil.