1. The most popular sports are soccer, baseball, and basketball. Recently, World cups were held in the world, a lot of people cheered for Japan and got interested in it more than in the past.
2. In Japan, there are many kinds of music, so especially they are not decided what the most famous genre is. However, I think pop music or rock band is very famous in Japan the most. If you have a chance to surf in the internet on Japanese songs, you should check them.