I have had a full brazillian wax before and yes, it hurt a little, but it was a comparable hurt to a large bandaid being ripped off rather than a lingering, aching hurt. The sting and sensitivity afterwards--which only lasted an hour at most--were definitely worth the feeling of being smooth and bump-free for a few weeks. I took a few painkillers about 30 minutes before my waxing appointment, so that may have helped. However, I don't think this is necessary unless you are very sensitive to pain or have never been waxed before and therefore don't know what to expect.
However, in the case of your wife, I would definitely suggest that she take some trimmers or scissors and clean up a bit before attempting to wax or shave. Always use a clean razor, the newer the better, and shave in the direction of the hair growth--not against it. Remember, she doesn't have to shave it all off at the first try.