"THE issue was the election of a Black Republican bent on excluding slavery from the federal territories".
perhaps you have heard of popular sovereignty ? the slave states were bent on creating new slave states so the issue was slavery not elections, which had they been united could have kept lincoln from being elected. the majority population was against slavery, not only in kansas, but the division created actually started the war which continued until secession and after kansas was admitted as a free state. popular sovereignty was not enough so the confederacy attempted to force slavery into the southern territories it claimed. the kansas-nebraska act and the southern win created the republican party which proved dominant. the south should have taken it's win and promoted slavery where it was wanted and lincoln might have never been a candidate or won the election. the bottom line was that the majority of population and states were anti-slave. even southern miners were against slavery in the territories and wanted it kept in cotton states of the old south. the issue was slavery.
on the morrill tariff... the south controlled the senate and could have stopped passage of the bill had they not vacated their seats prematurely . they might have controlled both houses if they had accepted their own proposal of popular sovereignty. the south passed the walker tariff and the tariff of 1857 , under which they still operated when they seceded. in trying to create new slave states and opposing the morrill tariff the south jumped the gun , so to speak. the fact that the majority population was becoming more and more anti-slave meant that the southern power was going to decline, sooner or later, because the average guy did not want to compete with slave labor. in the south it was a catch 22 because they also could not and for the most part into modern times, stomach black and white equality.
the south had no industry to speak of and the import taxes paid were paid by northern merchants and collected in northern ports. the south was capital poor and did not improve their ports and most were shallow and without enough warehouses and enough market without extra transportation costs. the north was the majority market and had the capital for importing and marketing. although it is claimed that the south bought the majority of imports this is not true. most new railroads went west where the market for imports was not south. the south was largely self sufficient and only the planters bought imported items, mostly luxury items.
a final thought... if the issue were tariffs why has the race issue remained to current times.