Short answers, pulled from the story.
The Stars and Bars flag flew from the 4th of March 1861 to the 1st of May 1863. This design featured a circle of seven white stars representing the original states that formed the Confederacy.
William Tappan Thompson published an editorial on the 23rd of April 1863 championing the design featuring the battle flag on a white background. Confederate Congressman Peter W. Gray proposed the amendment giving the flag its white field.
The last Confederate flag lowered during the Civil War flew aboard the commerce raider CSS Shenandoah in Liverpool, England on the 7th of November 1865. Very few of these third flags were actually manufactured due to the timing near the end of the war.
General P. G. T. Beauregard changed the national flag after tactical errors occurred at the First Battle of Manassas near Manassas, Virginia where regiments could not distinguish between the two national flags. He resolved then to have the flag changed if possible or to adopt a battle flag entirely different from any state or federal flag.
Georgia and Mississippi removed the Confederate battle flag from their state flags though Georgia removed it in 2003 and Mississippi removed it in 2020. The new design of the Georgia flag still references the original Stars and Bars iteration of the Georgia flag.