- The north was concerned that the South would want to impose its "exclusive organization" on the whole Union. When the extension of slavery into western territories became a topic of discussion in Congress, these suspicions came true.
- The south was upset because Slavery became ever more controversial as it began to spread westward due to non-slaveholding white settlers' aversion to competing with slaveholders in new territory.
- I sadly don't know, and couldn't find anything about the abolitionists, so I hope someone else can help you out on that one!
