Eating can help you form a straight line faster. Eating can only make you eat at home, touching can make you carve faster, and touching can make you shop around. Novices don't need to know the function of the bar, as long as they know that the four cards out of the bar are actually equivalent to three cards in a lettering.
Note that Japanese mahjong cannot be combined with the above requirements. The above are just basic requirements, necessary and insufficient conditions ... it is also necessary to form a specific card type, which is the so-called fan type. See Baidu Encyclopedia Japanese Mahjong entry for specific fan types.
I recommend two tutorials about Rima, one is 79 Jun's Sina blog (Baidu seventh9) and the other is Witch Blog v2.0, both of which are good teaching materials. You can have a look if you are interested.