Belton wrote:I agree with Briggs-san. This is a difficult area. I've read whole essays about it! Sometimes I think I have understood and then... I'm unsure again.
A good explanation, but I think a little too advanced for someone still struggling with beginners lessons, and it doesn't really answer the poster's question.
So I just listened to the two podcasts in question.
Remember that が places stress on the subject, and its use in a question implies that it is the ONE THING that the person asking really wants to know. は, on the other hand, places stress on what follows it. So it seems to me that the difference in usage is as follows.
Lesson 12 (which uses は):
In Lesson 12, the person asking the questions wants to know what kinds of food the speaker likes. You like American food? Indian food? Italian food? It's about general preferences, and in her mind, since no one food is more important than any other, は is used (because when using は the stress lies on 好き rather than the subject).
Lesson 11 (which uses が):
Her interest is solely about ONE THING. Japan and its food. She has no intention of asking him about Indian food, Chinese food, whatever. The stress is on the subject, so she uses が.
If she were to use が in the questions in Lesson 12, it would probably seem like these questions were just coming to mind one-by-one, instead of a pre-planned search to find out his preferences.