How to use help. (Attack on Titan (2016))

1)I don't understand why they are needed, why run after me, like flying around the Titan, but do not do anything useful, in training saw that Armin gave additional container, in the education wrote that each character has unique abilities, but I don't understand how to use them. And what to snacht letters next to the icons? (With B, etc.)
2)I Wanted to ask, is there any website with translation training or telling the basics. English hard vosprinimaetsya