EDIT I loved your post, F6. There are so many good parts to Major Sherwood F. Moran's SUGGESTIONS FOR JAPANESE INTERPRETERS BASED ON WORK IN THE FIELD, but I'll just post one of my favorites here:
It may be advisable to give one illustration of how, concretely, to question, according to my point of view. Take a question such as this, "Why did you lose this battle?" (a question we asked on more than one occasion regarding some definite battle on Guadalcanal). A question presented in this bare way is a most wooden and uninteresting affair. The interpreter should be given leeway to phrase his own questions, and to elaborate them as he sees fit, as he sizes up the situation and the particular prisoner he may be interviewing. His superior officer should merely give him a statement of the information he wants. A man who is simply a word for word interpreter (in the literal sense) of a superior officer's questions, is, after all, nothing but a verbal cuspidor; the whole proceeding is a rather dreary affair for all concerned, including the prisoner. The conversation, the phrasing of the questions, should be interesting and should capture the prisoner's imagination. To come back to the question above, "Why did you lose this battle?" That was the question put to me to interpret (in the broad sense) to a prisoner who had been captured the day after one of the terrific defeats of the Japanese in the earlier days of the fighting on Guadalcanal. Here is the way I put the question: "We all know how brave the Japanese soldier is. All the world knows and has been startled at the remarkable progress of the Japanese armies in the Far East. Their fortitude, their skill, their bravery are famous all over the world. You captured the Philippines; you captured Hong Kong, you ran right through Malaya and captured the so-called impregnable Singapore; you took Java, and many other places. The success of the Imperial armies has been stupendous and remarkable. But you come to Guadalcanal and run into a stone wall, and are not only defeated but practically annihilated. Why is it?" You see that this is a really built-up question. I wish you could see the interest on the prisoner's face as I am dramatically asking such a question as that. It's like telling a story, and at the end he is interested in telling his part of it.
Brilliant.
EDIT here: I have to add this one too:
On another occasion a soldier was brought in. A considerable chunk of his shinbone had been shot away. In such bad shape was he that we broke off in the middle of the interview to have his leg redressed. We were all interested in the redressing, in his leg, it was almost a social affair! And the point to note is that we really were interested, and not pretending to be interested in order to get information out of him.