Short answers, pulled from the story.
In ancient Greek, the name Hades meant the unseen one. Modern linguists trace this root back to the Proto-Greek form Awides while some scholars like Martin Litchfield West argue it originally meant the one who presides over meeting up.
Hades was the eldest son of Cronus and Rhea yet became the last child regurgitated by their father after Zeus forced him to disgorge his siblings. Following their victory in the ten-year war known as the Titanomachy, Hades drew lots to divide realms and received the underworld which included any things beneath the earth.
Since saying word Hades was frightening Greeks started referring to him as Plouton meaning the rich one derived from word Ploutos. When propitiating Hades people banged hands on ground to ensure he would hear them rather than looking directly at altar because simply pronouncing his name invited unwanted attention from the god who rarely left underworld domain.
Orpheus once descended into the underworld searching for his late wife Eurydice who died when a snake bit her. His music charmed even Hades and Persephone allowing him to take Eurydice to land of living as long as he did not look back at her on way out.
Hades appeared infrequently in artwork because Greeks feared him so much that depictions were not concretely thought of as deity during Archaic period. On pottery he has dark beard presented as stately figure seated upon ebony throne with attributes including bident less commonly scepter helm cornucopias roosters and key playing doubly symbolic role representing control over underworld.