based on their own convictions. Don't underestimate the commonality people in general share, and especially people with the mindset of this movement. I have found the same with Occupy, where a set of long discussions with my very rightwing neighbour led to us to find so much agreement that he joined me in a meetup. At the end of the day, we're all people trying to make do and provide a future for our children.
Why do you need the assurance people will vote in a certain way at some point? I think one only needs that if you want to engage in party politics. That is, some "leader" gets a mandate to negotiate with "the other side" and then needs the votes to back him up.
But once you have established that "leader", he has concentrated power and his corruption becomes more likely and more effective and corruption of the process more easy.
It looks like the movement is not looking to get support from or give support to the existing parties. But I'll be very very surprised if they didn't come up with some good proposals that they themselves support almost unanimosly, and that others will have a hard time not joining. It will all be on a case-by-case basis.
I do understand your comment, but think of it like this: OWS was blamed for not having a soundbitey solution or set of demands, and it was certainly messy at times. That doesn't detract from OccupyTheSEC filing a lawsuit against the bank regulators for failing to do their job, or from OccupySandy bringing relief with thousands of volunteers. My point is, total coherency is not needed to get things moving.
It's essentially the message Thom Hartmann always brings: remember, democracy begins with YOU. Get active and DO something. Anything really