Bungie should just copy what SWTOR did for cutscenes, excluding the dialogue wheel.

They've said that they are building the game to accommodate you and your fireteam, so yes, I think there definitely will be.

This question has been on my mind for quite some time. Given the fact that co-op is a major feature, I think co-op scenes are important. However, it's likely we'll only see them in the easier scripted smaller cutscenes. Because for the more complex cutscenes, it's not as simple as having the other player's characters just standing there. Although it's possible, these scenes are heavily scripted to the point that a decent amount of time and effort would have to be put into adding one or two more players and animations for him/her to be a part of the fight and what not.