There are literally hundreds of karate styles. Shoto kan is arguably the most popular. It has most schools in the world compared to other styles.
The most popular type would be karate. Specifically, Taekwondo probably has more students than any other style.
The Korean style of Karate, Tai Kwon Do is the most common, followed by Shorin Ryu and Shotokan.
The number of forms or kata in a style varies from style to style. Your instructors can answer the question for your style.
Soccer, And Karate. The type of Karate they like is called Taekwondo.
Each style of karate has a 'Grandmaster' that is the highest ranked in that style. Typically each style has a single 10th Dan.
International Karate Orgainization- kyokushinkai-kan