Short answers, pulled from the story.
Albert Einstein worked as an examiner at the Swiss Patent Office in Bern, Switzerland during 1905. He wrote most of these papers in his apartment on the first floor above Kramgasse street.
The first paper titled On a Heuristic Viewpoint Concerning the Production and Transformation of Light arrived at the journal office on the 18th of March 1905. It was published nine days after receiving it on the 9th of June 1905.
Einstein derived expressions for the mean squared displacement of particles using kinetic theory of gases to give experimentalists a way to count atoms by looking through an ordinary microscope. This statistical discussion convinced Wilhelm Ostwald of the existence of atoms following Jean Perrin's subsequent Brownian motion experiments.
A fourth paper titled Does the Inertia of a Body Depend Upon Its Energy Content? led Einstein to deduce what is sometimes described as the most famous equation E equals mc squared. The equation sets forth that energy of a body at rest equals its mass times speed of light squared.
Albert Einstein won the Nobel Prize in Physics in 1921 specifically for his work on photoelectricity. The article On a Heuristic Viewpoint Concerning the Production and Transformation of Light was the only specific discovery mentioned in citation awarding him the prize.