Short answers, pulled from the story.
Mars 3 began transmitting 90 seconds after landing on the 2nd of December, 1971, but transmission stopped after just 20 seconds for unknown reasons. The only data returned was a partial image of 70 lines described as "a gray background with no details." The powerful dust storm present at the time may have caused a coronal discharge that damaged the communications system.
Mars 3 landed on Mars on the 2nd of December, 1971, making it the first spacecraft to achieve a soft landing on another planet. The descent module was released at 09:14 UT, four hours and 35 minutes before reaching Mars.
Combined with Mars 2, the Mars 3 orbiter returned data showing mountains as high as 22 kilometers, surface temperatures ranging from -110 to +13 degrees Celsius, and surface pressures of 5.5 to 6 millibars. Water vapor was found to be 5,000 times less concentrated than in Earth's atmosphere, and dust storm grains were detected as high as 7 kilometers in the atmosphere.
The PrOP-M was a 4.5-kilogram rover aboard the Mars 3 lander, designed to move across the Martian surface on skis while connected to the lander by a 15-meter umbilical cable. It carried a dynamic penetrometer and a radiation densitometer, and used metal rods for autonomous obstacle avoidance. Whether it was ever deployed is unknown due to the lander's communication failure.
The lander's communication was lost just 20 seconds into transmission, possibly due to a coronal discharge triggered by a severe planet-wide dust storm. The Mars 3 orbiter also suffered a partial fuel loss, preventing it from reaching its planned 25-hour orbit and placing it instead in a 12-day, 19-hour elliptical orbit.
On the 11th of April, 2013, NASA announced that the Mars Reconnaissance Orbiter may have imaged the Mars 3 hardware, including the parachute, retrorockets, heat shield, and lander. The discovery was made by amateur space enthusiasts searching publicly available archived images captured by the HiRISE camera.