Short answers, pulled from the story.
The origins of ice cream are obscure, but some sources trace frozen desserts to Persia as early as 550 BC. The Heian period in Japan saw shaved ice served with sweet syrup to the aristocracy. By the 16th century, the Mughal Empire was using horsemen to bring ice from the Hindu Kush to Delhi to make kulfi.
The first recipe for ice cream in English was published in Mrs. Mary Eales's Receipts, in London in 1718. It called for tin ice-pots filled with cream or fruit, packed in a pail layered with ice and bay salt, and left in a dark cellar for four hours.
The first written suggestion to serve ice cream in a cone appeared in Mrs. A. B. Marshall's Book of Cookery in 1888, calling the recipe "Cornet with Cream." The cone's popularity in the United States grew sharply at the 1904 World's Fair in St. Louis, Missouri, where a legend holds that a Syrian waffle vendor began rolling waffles into cones for a neighbouring ice cream seller.
Neither introduced ice cream to America, though both are associated with its early history. Jefferson helped introduce vanilla ice cream specifically, and First Lady Dolley Madison served ice cream at President James Madison's Inaugural Ball in 1813. Confectioners were already selling ice cream in New York and other cities during the colonial era.
The US FDA requires ice cream to contain more than 10% milk fat, plus 6 to 10% milk and non-fat milk solids, 12 to 16% sweeteners, 0.2 to 0.5% stabilizers and emulsifiers, and 55 to 64% water. Products that do not meet these criteria are sometimes labelled "frozen dairy dessert" instead.
Agnes Marshall was an English cookery writer regarded as the "queen of ices." She wrote four books on frozen desserts between 1885 and 1894, patented her own ice cream maker, co-invented the hand-cranked ice cream freezer in the 1840s alongside Nancy Johnson, and was the first person to suggest using liquefied gases to freeze ice cream after seeing a demonstration at the Royal Institution.