Short answers, pulled from the story.
The South Carolina Declaration of Secession, formally titled the Declaration of the Immediate Causes Which Induce and Justify the Secession of South Carolina from the Federal Union, was a proclamation issued on the 24th of December, 1860. It explained the state's reasons for withdrawing from the United States, four days after the brief Ordinance of Secession had formally dissolved the union between South Carolina and the federal government.
The declaration was drafted by a committee of seven members, with Christopher G. Memminger considered its primary author. The other committee members were F. H. Wardlaw, R. W. Barnwell, J. P. Richardson, B. H. Rutledge, J. E. Jenkins, and P. E. Duncan.
South Carolina's declaration identified 'an increasing hostility on the part of the non-slaveholding States to the institution of slavery' as its stated cause. Specifically, it charged Northern states with violating the Constitution by refusing to enforce the Fugitive Slave Act, which required the return of escaped enslaved people to their state of origin.
The historian Harry V. Jaffa argued in his 2000 book 'A New Birth of Freedom' that South Carolina omitted phrases about equality and consent of the governed because its leaders did not hold those beliefs. In no sense, Jaffa noted, could it be said that the enslaved people of South Carolina were governed by powers derived from their consent.
Tariffs and taxes are not cited as causes in the South Carolina Declaration of Secession. The only reference to taxation is a passing note that the Constitution counted enslaved people as three-fifths of a person when setting direct tax rates. Post-war claims that tariff disputes drove secession find no support in the declaration's text.
Georgia, Mississippi, and Texas each issued similar declarations when they seceded, following South Carolina's example. The South Carolina convention also produced a companion document, written by Robert Barnwell Rhett, which called explicitly on other slaveholding states to secede and form a new nation.