Short answers, pulled from the story.
Irvin McDowell is best known for commanding Union forces at the First Battle of Bull Run in 1861, the first large-scale battle of the Civil War, which ended in a humiliating Union rout. He was also blamed for contributing to the defeat at the Second Battle of Bull Run in August 1862.
McDowell was promoted to brigadier general in the regular army on the 14th of May 1861, a promotion aided partly by the influence of Treasury Secretary Salmon P. Chase, who was his mentor. He received command of the Army of Northeastern Virginia thirteen days later.
After the Second Battle of Bull Run, McDowell received no new assignments for two years. In July 1864 he was sent to command the Department of the Pacific, effectively removed from the main theaters of the war.
Yes. McDowell graduated from the United States Military Academy in 1838, and P. G. T. Beauregard was one of his classmates. Beauregard later commanded Confederate forces against McDowell at the First Battle of Bull Run.
The board of review commissioned by President Rutherford B. Hayes recommended a pardon for Fitz John Porter and attributed much of the loss at the Second Battle of Bull Run to McDowell. It depicted him as indecisive, uncommunicative, and inept, finding that he failed to forward intelligence about Longstreet's positioning to Pope.
McDowell is buried in San Francisco National Cemetery in the Presidio of San Francisco, California. He died of a heart attack on the 4th of May 1885 while serving as Park Commissioner of San Francisco.