LongHairGal,
Yes, they ask the questions just before the group is led off to change and get baptized. At that point, if you want to back out you would be doing so very publicly. Now, if they do it the way they did when I got baptized, then in the weeks before the convention, you would have sat down for two sessions with an elder, who will review many of the JW beliefs. They will ask a question and provide Bible texts, and you must answer the question using the texts so that everyone is assured that you have the JW answer for that question. In my experience, the elder is really there to help walk you through it. I don't think they really want to test your knowledge, they just want to make sure that the JW teachings have sunk in.