Short answers, pulled from the story.
Hurricane Katrina attained Category 5 status on the morning of the 28th of August 2005. The storm reached its peak strength at 1800 UTC that day with maximum sustained winds of 175 miles per hour and a minimum central pressure of 902 millibars.
The National Hurricane Center attributes 1,836 fatalities to Hurricane Katrina across multiple states. Louisiana recorded 1,577 deaths while Mississippi accounted for 238 fatalities, with additional deaths occurring in Florida, Alabama, Georgia, Ohio, and Kentucky.
A June 2007 report by the American Society of Civil Engineers indicated that two-thirds of the flooding was caused by multiple failures of the city's floodwalls. Major levee breaches occurred at the 17th Street Canal levee, the London Avenue Canal, and the Industrial Canal, leaving approximately 80% of the city flooded.
Investigators concluded that the U.S. Army Corps of Engineers was responsible for the breached floodwalls. Congress had tasked the Army Corps with designing and building the region's hurricane protection system under the Flood Control Act of 1965.
Over seventy countries pledged monetary donations or other assistance to help with Hurricane Katrina recovery efforts. Cuba and Venezuela were the first countries to offer assistance, followed by Kuwait which made the largest single pledge of $500 million.