Short answers, pulled from the story.
The waltz originated in German-speaking regions of Europe. Around 1750, the lower classes in Bavaria, Tyrol, and Styria began dancing a couples dance called Walzer. The word derives from a term meaning "to roll or revolve."
According to contemporary singer Michael Kelly, the waltz reached England in 1791. During the Napoleonic Wars, infantry soldiers of the King's German Legion introduced it to the people of Bexhill, Sussex, from 1804. Diarist Thomas Raikes wrote that "No event ever produced so great a sensation in English society as the introduction of the waltz in 1813."
The waltz was considered scandalous because of its closed position, in which partners held each other closely. A 1771 German novel described it as "the shameless, indecent whirling-dance of the Germans." The Oxford English Dictionary still described the dance as "riotous and indecent" as late as 1825.
The Hesitation Waltz was introduced in the 1910s by Vernon and Irene Castle. It incorporated pauses called hesitations, where the moving foot was suspended in the air or slowly dragged, and was danced to fast music. Figures derived from it, including the Hesitation Change and Cross Hesitation, are part of the International Standard Waltz Syllabus today.
International Standard Waltz uses only closed figures, meaning the couple never breaks their embrace throughout the dance. American Style Waltz, part of the American Smooth syllabus, permits figures where contact is almost entirely released, such as the Syncopated Side-by-Side with Spin and open rolls.
Mission priests in California banned the waltz until 1834 specifically because of its closed dance position. After the ban was lifted, a Spanish Waltz developed, combining movement in closed position around the room with a formation element involving two couples facing each other.