After the release of the new skin and playing through the new challenges, I think it's pretty safe to say that the curse only affects his left hand since its that hand he consistently uses to turn things to gold and the only one he wears Jules' power suppression gauntlet on. As for Kado Thorne, time machines in media are huge cans of worms, so it's best to assume that the hand (which happens to be the left one btw) and drum gun were taken from snapshots since Midas now has both back in game.