
Well, the southern economy was agrarian, based on monoculture exports, while the northern economy was industrializing. This means that the north and south had divergent economic interests, and any economic policy would either help the north and hurt the south, or vice-versa. So sectional conflict was always going to happen
That’s not really in contention. The north initially fought to prevent secession, with abolition becoming a secondary war goal as the war went on. This doesn’t mean that nobody in the north was anti slavery, though, or that no northern politicians or generals entered the war intending to end slavery