The Oracle Revelation called Voice of the Dead is causing my head to explode. When we look at Speak with Dead we see that it has a time limit, and a limit to the number of questions you can ask. Since talking is a free action unless the DM says otherwise, the practical limit is the number of questions.
Enter Voice of the Dead. You can use this ability for a number of rounds equal to your Oracle level, but there is nothing that says how many questions you can ask each round. I have no idea how this is supposed to work!
Do you get a full assortment of questions appropriate for your caster level each round? Do you get one question per round, or some other arbitrary number of questions? Do you get a number of questions appropriate for your caster level then the effect ends regardless of how many rounds you may have remaining? *confused*