I seem to be having a rather common problem but I'm not sure how to address it in my group. I'm in a university jazz program and am in one of the combo groups(mines up to eight people and is one of the largest). When it comes to paper work our piano player is the leader, and in rehearsal it's a split between the piano and bass player as they have been together for a long time and bounce ideas back and forth. However from experience and talking to several other musicians, sound guys(we like to play at a few local bars), and a few people who have watched us play it becomes obvious that as a whole the group doesn't listen to one another and that no one is in charge during a song. Many people think we need one of the horn players to set the mood, intonation, and other stylistic settings in a song. That he should lead the group in the music, even if someone else is in charge of the rest of rehearsal and well being of the group.

How can the group learn to trust and listen to each other, and who should be in charge? How can I bring this up with the group?

I am by no means exempt from these concerns about the group, but I would like to try and work on them on both a personal and group level. I mean we are playing in college to learn how to communicate and listen right?
It is easy, in a band situation, to get used to the status quo. So all members just go about their role and nobody wants to rock the boat.

You just need to talk about it, with all of them. Let them know what feedback you've had from those sound guys etc. and ask them for suggestions on how those issues may be resolved. You'll be rocking that boat, but it needs to be done.
I know I need to rock the boat but I'm just not sure how to resolve the issue, so asking them would be a good idea. I'm also the youngest and least experienced of the group so it's hard to know if they will take this kind of things seriously or just dismiss it.