1) I don't know too much about the school girl uniform. Would be kinda creepy if I did. But your explanation pretty much meets my image of a typical Japanese school girl. Socks are usually white but I've seen many black ones as well.
And as Joriental has said, some schools are very competetive about their uniforms. Many schools actually have big name designer companies design their uniforms.
2) Sushi, like steak in the US, is more like a special occasion food. As you know most sushi restaurants in Japan are considered expensive. When i go eat sushi in Japan I'm always ready to use 10,000Yen ($100US) per person. So I guess it depends if the family is wealthy or not, but on average I'm guessing we eat it like once or twice a month for the expensive sushi. When I was a student and had little money, I usually went to a cheaper tachi-gui (eat standing up) sushi place and it cost me like 3000yen ($30US) to eat and be satisfied. So I went 4 or even 5 times a month.
I'm sure it varies depending on how much you like sushi because I know people who eat sushi everyday and people who don't eat sushi at all but once or twice a month is my guess.
3) Funny you'd think it's rude for the Japanese to ask you if you can eat something. Because the Japanese would consider it rude not to be considerate of someone's particular diet, especially if that person is from another country. They don't want you to be uncomfortable or be forced to eat something because you don't want to be rude and say no to something.
I guess this is difference in culture....Western culture is pretty open and free on saying no or refusing somethng that is offered without it being rude. In Japanese culture it isn't considered rude necessarily to say no, but people tend to follow what the other people are doing so doing something or saying something that is different from what the others are doing is considered....strange. That's the only word I can think of.
Also I think many westerners have allergic reactions and are quite picky with their food. (My opinion not of the Japanese) I worked at a restaurant and caucasian customers would ask if there was any butter in the dish, any meat, any fish, any mayo. How is it cooked? Any alcohol?
I'm not saying that it's bad to be picky about your food but they are a lot more pickier about what they can eat and what they can't eat so I tend to ask if they are cool with whatever is served just to be safe.
I guess you can call it racism in a way because they are treating you differently because of skin color, but the aim of the treatment is to make you more comfortable at the table so I wouldn't say it was a bad thing necessarily.
As for the all gaijin speak english. This is true, most Japanese regard caucasians as American or British. Maybe Australian, sometimes French. This comes from not knowing better. Majority rules and the majority of the caucasians who live in Japan are usually either Americans or British and maybe Australian. Sometimes French. It certainly is a form of stereo-typing but I get that a lot in the US too because I'm Asian. Usually they think I'm Chinese and I don't consider it racism. It's just lack of knowledge.
Chopsticks is a hard one. I can see you considering it a racial issue and I do agree with you. Though it wouldn't bother me much. Let them think you can't use chopsticks and bust out your own pair and start eating. They'd be in awe.
Many caucasians I met in Japan could use chopsticks better than I could.
And Japan being the ONLY country with 4 seasons.
This is just ignorance on them. They've never visited places like Virginia or Washington DC. I always thought Japan had the best fall season in all of the world until I went to Richmond VA in late October. now I think Virginia is the best in the world!