Short answers, pulled from the story.
Nannerl was eleven and Wolfgang was seven when the Mozart family grand tour began on the 9th of July 1763. The young age was deliberate; Leopold believed the younger the children were, the more spectacular the demonstration of their gifts would be.
The Mozart family grand tour ran from 1763 to 1766 and covered western Europe, including Munich, Frankfurt, Brussels, Paris, London, the Dutch Republic, and Switzerland, before the family returned to Salzburg on the 29th of November 1766. The London stay alone lasted more than a year.
Around thirty pieces composed by Wolfgang during the tour survive, including his first symphonies (among them Symphony No. 1 in E flat, K. 16, and the D major K. 19), keyboard sonatas published as Opus 1 and Opus 2, the motet "God is our Refuge" K. 20, and the Gallimathias musicum K. 32 written for the Prince of Orange's coming-of-age concert.
The Mozart children performed before Empress Maria Theresa in Vienna before the tour, and during the tour before King George III and Queen Charlotte in London, King Louis XV's court at Versailles, Princess Anna Amalia of Prussia, Elector Palatine Karl Theodor at Mannheim, and Prince Charles of Lorraine in Brussels, among many other royal and noble audiences.
Leopold Mozart never disclosed the full accounts. The librarian of St Peter's Abbey in Salzburg estimated the tour's total costs at 20,000 florins, while the gifts and curiosities brought back were valued at around 12,000 florins. At its peaks, Leopold was able to deposit 2,200 florins after the Paris concerts and 1,100 florins after initial London successes.
When Leopold and Wolfgang left for Italy in December 1769, Nannerl, then eighteen, was left behind because she was no longer exhibitable as a child wonder. The German diplomat Grimm had praised her during the tour as having the finest and most brilliant execution on the harpsichord, but the subsequent years of travel and public display belonged to Wolfgang alone.