Short answers, pulled from the story.
Phobos was discovered by American astronomer Asaph Hall on the 18th of August 1877 at the United States Naval Observatory in Washington, D.C. Hall made the discovery using the 26-inch Great Equatorial refracting telescope, then the world's largest. He had found Mars's other moon, Deimos, just days earlier.
Phobos orbits Mars at an altitude of 5,989 km, closer to its parent planet than any other known natural satellite in the Solar System. Its orbit is so low that it cannot be seen from Martian latitudes greater than 70.4 degrees.
Phobos orbits Mars faster than Mars rotates, completing a full orbit in just 7 hours and 39 minutes. Because it outruns the planet's rotation, it rises in the west and sets in the east, crossing the Martian sky in 4 hours and 15 minutes or less.
The origin of the grooves has been debated since the 1970s. A 2018 computational analysis concluded the most likely cause is boulders ejected from the 9-km Stickney impact crater that rolled and bounced more than 360 degrees around the moon, compressing the soft regolith into long grooves. The grooves range up to 20 km in length and have been grouped into 12 or more families of varying age.
Tidal forces are gradually shrinking Phobos's orbit by approximately 2 metres every 100 years. In roughly 30 to 50 million years, the moon is expected to break apart when it reaches approximately 2.1 Mars radii from the planet. The loose material will form a planetary ring around Mars that could last from 1 million to 100 million years, while more cohesive fragments will fall into the Martian atmosphere.
The origin of Phobos is disputed. Its spectral and density properties resemble carbonaceous C- and D-type asteroids, suggesting capture, but its high porosity and phyllosilicate composition point toward formation from debris ejected by a large impact on Mars. A 2021 study led by Amirhossein Bagheri at ETH Zurich proposed that Phobos and Deimos both formed from a single parent body that was shattered by another object between 1 and 2.7 billion years ago.