Today I ran In the Belly of the Beast for the first time ever. Before entering the arena I made the deals with drider Rhitez (to kill drow Voltane) and with drow Zeslym Cay'Vorym (to kill mind flayer Idrigozak). To my surprise, Rhitez appeared among the attackers, I had to kill him, and I never saw Voltane or Idrigozak. When the quest was done, optionals "slay Voltane, the slavemaster" and "slay Idrigozak, the illithid high roller" were unchecked. Am I supposed to look for them, and is it a bug that Rhitez appeared? I thought once any one of these makes a deal, they do not attack.
Also, the optional "slay the purple worm in less than a minute" -- is that starting from when you are vomited out?