Ward Stavig's The World of Tupac Amaru: Conflict, Community, and Identity in Colonial Peru. Really is about the "world." Tupac Amaru enters in the last chapter. Parts on how he uses Inca/creole identity most interesting.
David T. Garrett's "'His Majesty's Most Loyal Vassals': The Indian Nobility and Tupac Amaru," from Hispanic American Historical Review. 84:4, 2004.
Looking for English translation of Tupac Amaru's letters. Also good study of wife, Micaela Bastidas.
trivia: those imprisoned and not executed after the insurrection were sent to Spain via the San Pedro Alcantara which went aground and sank near Lisbon and was the subject of Goya's El naufragio. Fernando, son of Tupac Amaru and Micaela Bastidas, survived the wreck.