Excellent point. Don't let Kerry get away with using the word "but". Focus on the decisions that Kerry has had to make other than marrying rich, he really hasn't been held accountable for anything he has done. Look for Bush to focus on bills with Kerry's name and lazy record of not doing anything or showing up when expected. That would put him back on his heels.
I just figured Kerry would be mentally aware of his using the word BUT all the time, and that could possibly throw him off-stride. It would also alert viewers to the tactic so they could have a bit of fun counting the number of times Kerry said one thing AND the opposite within the same answer.
By the way, I agree with you on Bush keeping the Kerry voting record in the forefront. It worked before.