I certainly hope that the only point of cultural curiosity we experience in Japan is not limited to sexual topics. I mean, it is a worthy topic, but hardly the only one we could choose. For example, point number 3 in the OP mentions food.
For my part, the whole concept of shiokara (fermented squid guts, miso paste, and diced bits of boiled squid) is a bit daunting. The taste is one of the single most revolting things that I have ever attempted to stomach on more than one occasion.
Of other things that gave me a bit of the "What the . . . ?" came about when I went to get my nihon no unten-menkyoshou (Japanese driver's license). A five-month long process with multiple tests and a total cost easily greater than 5-man-en? ARGH!
Anyway, just my 2-yen worth of thoughts.