Stops on Manaus - Santarém - Belem boat trip

Is there any way to know where / when the boats on Amazon river will stop? Or does it depend on passengers and where they want to embark / disembark?

I found information on some blogs that it stops "in at least one port a day", but except bigger ports (Manaus, Santarém and Belem) I haven't found anything.

And is it possible to leave the boat in one of those places and embark another one on the next day (assuming there is something interesting there, I wouldn't stop in a random river Indian community). If I understood correctly, every boat is managed by a different company, so I guess it would be necessary to buy two tickets.