Much of this will have to be driven by your own opinion about the work. This will have to come from reflection and thought about the work and what it means to you. I think that one of the most pressing issues I would want to ask Sophocles is how he felt in constructing a character that endures so much in way of suffering. From a literary and dramatic level, it is difficult to find a character that endures more than Oedipus does. I would want to know if Sophocles felt any pity or mercy towards him in constructing him, or if he felt that the lessons learned from Oedipus would be strong enough so that individuals needed to see a portrait of intense suffering without any mitigation. I think that another level of questioning that I would want to know similar to this would be where Sophocles' inspiration for Oedipus resided. Seeing that Oedipus becomes a significant archetype for all drama and all that comes from it, I would want to know what served as inspiration for him and from where he derived it in developing the character of Oedipus. If I were to ask Sophocles anything in this domain, it would reside in this setting.