From what my impression is of the exam so far, if you got to D, you will be fine. Reading the discussions on the forums, the reasoning for (A) is a bit of a logical stretch and I don't think such a question would appear on the actual exam.
I've been informed that all of the test prep companies do a very poor job of emulating the GMAT's style for Verbal questions, and that it's best to stick with official questions. I know that those run out quite quickly, so it's quite normal to use other sources, but for questions like these, I don't think it's worth stressing over. I really think you should feel comfortable with having chosen D.
As for a session, are we waiting until next weekend or does during the week work for you guys? (I'm not sure how early you have to sleep, Vaibhav)