On pg.3, Miyamoto says that Kawai is a former Pachinko Pro. A Pachi-pro is someone who makes money from pachinko rather than playing for fun, and they do this by sharing strats and learning how the machines work to maximise their chances of winning. Some examples are playing during promotional periods of newly released machines with enhanced odds, knowing when a machine is hot, using skill-shots to place the balls where they want, etc.
Soba. Very versatile and very much appreciated in Japan. You can eat it hot or cold, in noodle form with hot soup or chilled with cold dipping soup in the summer. Eating it cold lets you feel the textures and hardness of the noodles better, I personally think cold foods are more flavorsome. The soba which comes in a cup means you can choose how wet your soba is before you eat it (by dunking it), then you can drink the rest of the soup.
pg.17, Yanauchi-san pours a cup of sake for Foreman while asking him for a favor, and you see Numakawa and Isawa sweat. Drinking etiquette in Japan: pouring between business partners where the senior pours for the junior, the junior should immediately offer to pour back. Foreman doesn't get the chance to do it before he leaves though, so I guess he's sort of forced to look after Kawai now. I believe most of the time the senior initiates this.
Also, note the sweater he's wearing. It has the number '0' on it while in chp.38 (In Tokyo), it had the number '24'.