Re: Winter Soldier: Bionic arm or not?
Yes to the bionic arm. Or they could make it some kind of armor like Thor's or more like an exoskeleton/frame that enhances his normal (or atrophied) arm.
Regarding the mask, I don't think he needs a domino mask. I can see him wearing a full mask, balaclava, or a mask that has the hair exposed while on a mission. Maybe while tangling with Cap for the first time, the mask is damaged a bit which exposes part of Bucky's face.
I like the idea of having a sequence (mission or chase) that goes through a masquerade party. WS could grab a mask off someone to help hide his identity so he can escape. It would be a nice wink to fans without alienating new viewers with the cheesiness of a domino mask.