Short answers, pulled from the story.
The first royal residence on this site, known as the Domik Petra I, was built in 1704. The fourth and final Winter Palace emerged from the vision of Empress Elizabeth with work beginning in 1732.
Architect Francesco Bartolomeo Rastrelli transformed the core structure into a colossal elongated rectangle painted straw yellow with white and gilded ornamentation. Later additions included massive grey granite columns added during Nicholas I's reign.
A fire broke out in 1837 within the Winter Palace destroying most of its interior while the cause remains unknown. The rebuilding process took less than one year despite severe winter conditions and involved six thousand workmen laboring continuously.
Empress Catherine the Great transformed the Winter Palace into a world-class repository through aggressive acquisition strategies between 1764 and 1781. She purchased six major collections including those of Johann Ernst Gotzkowsky and Heinrich von Brühl containing works by Rembrandt and Rubens.
On the 30th of October 1917, the Winter Palace was declared part of the Hermitage public museums. The first exhibition concerned the history of the revolution allowing public viewing of imperial private rooms.