I calculated a house edge of 0.64%. The game is very similar to a video poker game called "Double Down Stud Poker" by IGT. This house edge does not take in to account other player decisions, which could potentially make it better for the player. For instance, if there is "A 6" showing and someone else doubles, you could guess that they have an Ace or a Joker and adjust your own strategy.
It's getting to me, so I will probably finish working out the strategy (minus the other player interactions).
I heart Crystal Math.