What is "Osechi"? Is it a special Japanese dish?

Is Christmas in Japan celebrated as extensively as in America? Or what is the ‘biggest event’ for most Japanese people?

What is the most popular sport played by regular (non-professional) Japanese people?
What is the most popular hobby enjoyed by regular Japanese people?

As a visiting teacher I will be staying Japan for 3 months and am looking for an accident insurance for bicycle ride, which is required by the prefecture I will be staying. Is there any insurance services that can cover me? I don’t speak Japanese so need a service in English. If possible, I would like to apply for the service online. Thanks!