Short answers, pulled from the story.
The D&D dwarf draws from Norse and Teutonic mythology, including the Germanic story The Ring of the Nibelungen and the Brothers Grimm fairy tale "Rumpelstiltskin." J. R. R. Tolkien's version of the dwarf is the most direct influence, alongside Poul Anderson's 1961 novel Three Hearts and Three Lions. Dwarves were introduced into Chainmail, the forerunner of D&D, in the early 1970s.
Dwarves first appeared as a player character race in the original 1974 edition of Dungeons and Dragons. In that edition, dwarves could only play a fighter and could not advance beyond the sixth level. The 1976 supplement Greyhawk expanded their options to include the thief class with no level restriction.
More than a dozen dwarven subraces have been described across D&D's publishing history. These include hill dwarves, mountain dwarves, deep dwarves, duergar, frost dwarves, glacier dwarves, seacliff dwarves, badlands dwarves, dream dwarves, and setting-specific variants such as the Athasian dwarf and Dragonlance's gully dwarves.
Dwarves in D&D usually worship Moradin, whom dwarven legend names as their creator. According to those legends, Moradin fashioned the dwarves in his own likeness from gems and metal, then breathed life into them. The broader dwarven pantheon includes Abbathor, Berronar Truesilver, Clanggedin Silverbeard, Dugmaren Brightmantle, Dumathoin, Muamman Duathal, and Vergadain.
Dethek is the dwarven runic writing system first described in the first edition Cyclopedia of the Realms, released with the Forgotten Realms Campaign Set in 1987. The name translates directly into "Common." Dwarves using Dethek inscribe on metal or stone, with tablets called runestones that are diamond-shaped and read from the outer edge spiraling inward.
Yes. The depiction of dwarves in Dungeons and Dragons has been cited as the direct inspiration for the dwarves in World of Warcraft. D&D's codification of dwarven traits, including combat hardiness, underground expertise, and metalworking culture, carried the archetype from the tabletop into one of the most widely played digital games ever made.