These are events in the play. He introduced the second actor. While his characters are somewhat two dimensional his plays are very theatrical with lots of spectacle, costumes, props, etc. The Oresteia is one of the great drama cycles. Unending chain of guilt and revenge.
Man takes revenge, gods take justice.
He won 24 contests and in 468 he beat Aeschylus. His work questions religious beliefs, questions moral stability and focuses on ideas over character.