Re: How to address a Shihan, Sempai, or Sensei?
Just a side note (because I haven't seen it mentioned):
Different Martial Disciplines veiw the above rule differently.
In Judo, there is only one Shihan (Kano, Sensei) but he is still not referd to as that title.
In certain family styles of Kenpo (Ga-san ryu and Fuji ryu for example) The head of the family style system, or ryu, is Shihan and they ARE refered to by that title, not sesnei. I specifically asked one of their seniors (he was Japanse) if this was proper and I was told it was for this case. It separates the level of teachers in their hiarchy.
By definition, I believe "Sensei" means one who has gone before you or "born before". The Japanese use this term for their Doctor, the man expertly cutting fish in the market, sushi chefs, school teachers, and just someone older than you.
Shihan means basically, an instructor or teacher who understands the system enough to duplicate other students to sensei level. Basically "Master Instructor."
I have heard it described to "gaijin" as "Sensei is like having a doctorate (like a professor at University) and Shihan would be head of the department (The head of the Science Dept.). Both are called Doctor".
Best rule of thumb: You can never bow too much and you can't go wrong by calling someone Sensei.