Kosaku
First, the complimenting of the chopsticks thing: I do not see why you are bothered by this. If you see someone come to America struggling to learn this culture, do you not compliment them? And a good comparison would not be the fork. Forks are used internationally (especially in the increasingly Americanized country of Japan). Also, you have to be insanely idiotic not be able to learn how to use a fork in an instant (or by instinct. You just stab at food with it; how hard is that?). In comparison, being learned at using chopsticks shows some effort to learn the Japanese culture.
As for the language thing, don’t be offended. It’s just the culture. It is not rude, and it is not a laugh at you, but more of a laugh with you. Also, I believe the Japanese are not as sensitive as Americans. There’s a lot of joking around about things Americans would be very offended at. I suggest you learn to take it and like it.