Short answers, pulled from the story.
The Grammy Award for Best Rock Performance was first presented at the 54th Grammy Awards in 2012. It replaced three earlier categories: Best Solo Rock Vocal Performance, Best Rock Performance by a Duo or Group with Vocal, and Best Rock Instrumental Performance.
The Recording Academy merged three existing rock categories into one to reduce the total number of Grammy categories. The Academy argued that distinctions between solo and group rock performances were difficult to justify because, in their words, "four-fifths of rock acts are groups, and even solo rock acts tend to be backed by a band."
Brittany Howard leads with six nominations in the Best Rock Performance category, four of those coming with Alabama Shakes and the rest as a solo artist. Foo Fighters are next with five nominations.
Yes. Starting in 2014, the Best Rock Performance category incorporated hard rock recordings that had previously been eligible for the Best Hard Rock Performance and Best Hard Rock/Metal Performance awards. Both of those prior categories were discontinued.
David Bowie won in 2017 for "Blackstar," Leonard Cohen won in 2018 for "You Want It Darker," and Chris Cornell won in 2019 for "When Bad Does Good." All three wins came after the artists had died.
The award itself goes to the artist. Producers, engineers, and songwriters associated with the winning recording are not presented the Grammy statuette but can apply separately for a Winners Certificate.