There were never any tariffs on Southern-produced goods. Tariffs are on imports, not exports.
Had secession succeeded, the US would have had a balance of payments problem, since cotton formed the majority of exports, but it is very doubtful the seceded states (with 1/4 of the population) consumed even a majority of the imported goods which had tariffs on them.
You miss the point. In 1860, 65% of the value of US exports was in cotton and tobacco. Whether or not Southern states exported and imported, paying tariffs, or Northern traders and brokers bought, shipped and re-imported, thus paying tariffs, is not the issue. The point is that in 1860, 65% of the US Treasury revenue came from tariffs on imported goods paid for in Europe with Southern grown goods. With cotton and tobacco no longer going through US Customs houses, the government was almost immediately bankrupt.
You are correct. However, the tariffs were to prevent southerners from buying cheaper goods and to force them instead to buy more expensive goods manufactured in the north. When you consider that the tariff on goods covered by the Morrill Act approached 47%, that leaves a lot of room for price-gouging by the north, which is exactly what happened.
Further, many southern exports had to pass through northern ports before being shipped overseas, thus further impoverishing the south.
One has to wonder how much longer slavery in the south was prolonged by northern economic aggression in the decades leading up to the Civil War. Slavery in the north died out not only because of the abolitionists but also because it was no longer economically viable.