1. Not that I can see. "dialogue" goes with "discourse".
2. More or less. "disorder" is stronger than "irregularity".
3. Not to me. "limitless" woud suggest spatial expansion. "unfinished" means that there's one more thing to be said, and then another, and then another, etc.
4. Maybe. It's hard to say without being familiar with the connotations that the pair "discourse