Short answers, pulled from the story.
Elizabethan Baroque is the name for the Russian Baroque architectural style that developed during the reign of Elizabeth of Russia, between 1741 and 1762. It is also called style Rocaille or the Rococo style, though it is not quite correct to regard it as true Rococo.
The Italian architect Francesco Bartolomeo Rastrelli was the key figure of Elizabethan Baroque, so central to it that the style is also called Rastrellian Baroque. The Russian architect Savva Chevakinsky was another renowned figure working in the style.
Rastrelli designed the Winter Palace, the Catherine Palace, and the Peterhof Palace, majestic complexes in and around St. Petersburg. His most spectacular work was the Smolny Convent, whose model shows an immense pyramidal steeple that was never actually built.
Unlike the earlier Petrine Baroque, Elizabethan Baroque returned to the Muscovite Baroque tradition and kept Russian architectural elements such as the five cupolas shaped like onions. It favored architecture of grandeur meant to glorify the might of the Russian Empire.
Rastrelli was influenced by the French architects Germain Boffrand and Robert de Cotte, by Central European architects including Balthasar Neumann, François de Cuvilliés, Matthäus Daniel Pöppelmann, and Fischer von Erlach, and by the monasteries of Moscow and the Italian Baroque of Gian Lorenzo Bernini.
After Elizabeth Petrovna's death, construction orders passed to Antonio Rinaldi, who had previously worked at the Oranienbaum Palace. Rinaldi introduced the Rococo style into the court's architecture, and in the years following 1760 he and other prominent architects abandoned Baroque for Classicism.