Some decent quality of life stuff there, but my Number 0 (Highest priority)
0) Make co-op dialogue more cooperative!
When one player begins a conversation and the other player is within range, give the other player a pop-up that allows them to join the conversation. If they join the conversation, then they have equal chance to ask questions and select from the dialogue tree. If one player selects before the other player, they get a message like "waiting for input from other player". A random roll is made as to decide who wins. Save the rock, paper scissors for major decisions as they are now. If a player declines to join the conversation, it works like it does today.
I hate to say it, but take a look at how Bioware implemented conversations in SW:TOR. It works well mechanically.
