Short answers, pulled from the story.
Eli Whitney invented the cotton gin in 1793. The device used a wooden drum fitted with hooks to pull cotton fibers through a mesh, separating the fibers from the seeds. He applied for the patent on the 28th of October 1793 and received it on the 14th of March 1794.
Whitney made very little money from the cotton gin. His cotton gin company went out of business in 1797 after patent infringement lawsuits consumed the profits. His New Haven factory burned down and litigation left him near bankruptcy, despite later state payments from South Carolina ($50,000), North Carolina (roughly $30,000), and Tennessee (reportedly around $10,000).
The cotton gin made growing cotton with slave labor highly profitable, reviving and expanding the Southern plantation economy. Cotton exports rose from fewer than 500,000 pounds in 1793 to 93 million pounds by 1810, and cotton represented more than half of total U.S. export value from 1820 to 1860. Some historians argue the invention was an unintended cause of the Civil War by sustaining slavery at a critical point in its development.
Whitney did not invent interchangeable parts; the idea predates him by centuries, with traces back to the Punic Wars. His role was one of promotion rather than invention. Historian Merritt Roe Smith concluded that Whitney's 1801 demonstration for government officials was staged. Other New Englanders, including Captain John H. Hall and Simeon North, achieved true interchangeability before the Whitney armory did.
Eli Whitney died on the 8th of January 1825, in New Haven, Connecticut, one month after his fifty-ninth birthday. The cause of death was prostate cancer. During his illness he reportedly invented mechanical devices to ease his pain.
Whitney attended Yale, entering in the fall of 1789 and graduating Phi Beta Kappa in 1792. He prepared at Leicester Academy (later Becker College) and under the tutelage of Reverend Elizur Goodrich of Durham, Connecticut. Yale's admissions program for non-traditional students is named in his honor today.