1) Asoko is a generic "over there", mukou means "across": across the street, on the other side of the mountain pass, on the other side of the curtain and so on (i.e. it doesn't have to be far away).
3) Yobu means "to call", as in to call for someone to come over ("Hey, come look at this"), or to be called by a certain name.
2) As far as I remember my teacher said that though both seem to mean the same, as in "learning something" the difference is in what way you do it. narau means you learn something by practicing and has a more "forced" feeling to it while manabu has a more naturally learning, or getting used to something feeling about it. So you would could use narau to say that you spend the whole afternoon learning new vocabulary and manabu to express that you learned something by experience or maybe that you learned a new word through your favorite Dorama because it just stuck with you.
(hope that wasn't too complicated an explanation ^^")