Now that Kira has been mentioned, i'll mention something else: is Odo still around?
Yes and no. He does make a guest appearance in a few books (but it's not mentioned that it's him until the end of one of them), and he also apparently sent a Jem'Hadar onto the station to expose him to the Federation lifestyle.
I have a question about this episode; Seeing that all Cardassian missions are set for Captain and above, does that mean episode 15 is only Captain and above? or have things been changed to allow lower ranking players access to the quests??
What level or faction do I need to be in order to play the episode?
Feature Episodes can be played by both Federation and Klingon faction characters that are at least level 6. The Breen series is the only exception which requires players to be level 10.
I would think (hope) that Cryptic would not want to change that practice significantly for this FE because doing so would limit participation -- and that would be bad.