Regarding Joker as the leader, I'm also still not finished with the game (I've finished the fifth palace), but I agree with people who say that Makoto feels like the leader so far. A lot of people say that the end of the game changes their opinion regarding this, and that may very well be true, but then you still go through 90% of the game with Joker not acting like a leader.
I feel like Makoto's role has been greater than that of just a strategist -- she often represents the group, leads discussions, and tries to resolve conflicts. Joker hardly says anything, and even when he does, it's often of little consequence, and quite a few of the possible options are jokes. I feel like most of the leader-like things that Joker does (deciding when to do things, leading combat) show up only as gameplay, and aren't reflected at all in the story scenes, where I just see Makoto doing everything.
Of course, I'll still keep an open mind and see how things play out, but when considering only what I've seen so far, I'd hardly consider Joker to be the leader.