Actually I think preparing your answers in advance is not necessarily a bad thing. I did just that and got through. After browsing through all (yes all) of the pages of this thread, I came up with a very comprehensive list of sample questions, wrote an answer to all of them, and rehearsed them relentlessly. Just keep in mind that not every question requires a description of a military mission as an answer. Short answers are more likely to do the job. The assessors know that not every day is a thrilling adventure and not every problem requires rocket science to solve it. They just want to get a general idea of your experience and exposure.
Don't rehearse the answers word for word. It will be noticed.
As for the bull****ometer alarm - very sound point indeed. As with every situation in life, never tell a lie - that way you don't have to remember what you said!
