Short answers, pulled from the story.
The first Oval Office in the West Wing was built in 1909 under President William Howard Taft. It was designed by Nathan C. Wyeth and centered on the south facade of the expanded West Wing.
The oval shape traces back to George Washington's bow window salon in Philadelphia, where he received guests standing before three curved windows. Architect James Hoban, who visited Washington in Philadelphia in June 1792, incorporated an elliptic salon into his White House design. The association between the presidency and an oval room persisted for over a century before Taft formalized it in the West Wing in 1909.
Roosevelt, who used a wheelchair, had architect Eric Gugler relocate the Oval Office to the southeast corner in 1933-34 to give him more privacy and easier access to the White House residence. The two-chair arrangement in front of the fireplace was also devised so Roosevelt could sit at the same level as his guests, de-emphasizing his inability to stand without assistance.
The Resolute desk was built from the timbers of the British ship HMS Resolute, which was trapped in Arctic ice in 1854 and later recovered by an American whaling vessel. Queen Victoria gifted the desk to President Rutherford B. Hayes in 1880. Jacqueline Kennedy moved it to the Oval Office in 1961, and Jimmy Carter returned it there in 1977 after a period on loan to the Smithsonian Institution; it has been used by all presidents since Carter except George H. W. Bush.
Notable Oval Office addresses include John F. Kennedy announcing the Cuban Missile Crisis in 1962, Lyndon B. Johnson announcing he would not seek reelection in 1968, Richard Nixon announcing his resignation in 1974, Ronald Reagan speaking after the Space Shuttle Challenger disaster in 1986, and George W. Bush addressing the country after the September 11 attacks in 2001.
A portrait of George Washington has been displayed by most presidents, typically the Rembrandt Peale Porthole portrait or the Charles Willson Peale three-quarter-length portrait, hung over the mantel. Frederic Remington's bronze The Bronco Buster has been displayed by more presidents than any other sculpture, appearing in the offices of Johnson, Ford, Carter, Reagan, Clinton, George W. Bush, Obama, and Trump.