Short answers, pulled from the story.
Ohio-born Daniel Decatur Emmett is credited by most sources with composing "Dixie," though no fewer than 37 people had claimed authorship by 1908. Bryant's Minstrels premiered it in New York City on the 4th of April, 1859, at Mechanics' Hall, billed as a plantation song and dance.
Firth, Pond & Co. paid Emmett $300 for all rights to "Dixie" on the 11th of February, 1861. Emmett had already published the song through the same company on the 21st of June, 1860, but his delay in registering the copyright allowed the song to proliferate among rival publishers before that payment was made.
"Dixie" was played at the inauguration of Jefferson Davis on the 18th of February, 1861, arranged as a quickstep by Herman Frank Arnold. Before that, a band had played it after each vote for secession at St. Andrew's Hall in Charleston, South Carolina, on the 20th of December, 1860.
Abraham Lincoln was a known admirer of "Dixie" and had it played at some of his political rallies. On the 10th of April, 1865, one day after General Robert E. Lee's surrender, Lincoln requested the song before a White House crowd, declaring that the Union had "fairly captured it."
Ben and Lew Snowden were Black musicians from Mount Vernon, Ohio, who residents claimed collaborated informally with Emmett on "Dixie." Researchers Howard L. Sacks and Judith Sacks proposed that Emmett may actually have worked with the Snowdens' parents, Thomas and Ellen, since Ben and Lew would have been small children in 1860. When Lew Snowden died in 1923, he owned a framed photograph of Emmett inscribed "Author of 'Dixie'!"
In 2016, the Ole Miss athletics department announced that "Dixie" would no longer be played at athletic events, ending a tradition that had spanned roughly seven decades at football games and other sports. Athletic director Ross Bjork cited the university's core values and the goal of ensuring all people feel welcome.