Short answers, pulled from the story.
The M1 Abrams is a third-generation American main battle tank designed by Chrysler Defense, which is now General Dynamics Land Systems. It is named for General Creighton Abrams, who set the weight specification for the design at 53 tons during development in the early 1970s.
The M1 Abrams entered U.S. Army service in 1980. A total of 3,273 M1 Abrams tanks were produced during 1979-1985, with low-rate initial production approved in May 1979.
The M1 Abrams uses an AGT1500 multifuel gas turbine engine producing 1,500 horsepower. At its worldwide debut during the 1982 Reforger exercise, soldiers noted that the turbine produced only a high-pitched whine rather than the loud rumble of a diesel engine, which is how the tank earned the nickname "whispering death".
Chobham armor, also called Burlington armor, is a secret British-developed composite consisting of ceramic blocks set in resin between layers of conventional armor. The M1 Abrams was the first American tank to use it. The ceramic acts as a non-explosive reactive material that disrupts shaped-charge jets and erodes kinetic penetrators; at the hull front it reaches a thickness of about two feet.
In the Gulf War's Operation Desert Storm in 1991, the U.S. Army deployed 1,956 M1A1s. No Abrams was destroyed by enemy tank fire. Of 23 M1A1s damaged or destroyed, nine were total losses: seven from friendly fire and two intentionally destroyed to prevent capture. The Abrams could engage targets beyond 2,500 meters while Iraqi tanks were effective only within 2,000 meters, giving U.S. crews a decisive range advantage.
Urban combat in the Iraq War exposed the Abrams to attacks from all directions, including short-range rockets aimed at tracks, rear panels, and top armor. By March 2005, approximately 80 Abrams had been forced out of action. The Tank Urban Survival Kit added reactive armor to hull sides, slat armor at the rear, a transparent gun shield, and an exterior infantry telephone to address these vulnerabilities.