The imperative ending -u is used not only (as we have already seen) in direct commands and so on, but also in indirect speech in clauses introduced by ke after verbs of commanding, requesting, advising, whishing. (These often correspond to English clauses with "to".)
The preposition je is kind of a joker. It has no precise meaning, but is used where no other preposition covers the exact meaning one wishes to express. Amongst other things, it is the usual word for translating "at" when telling the time.
This verb is mainly used in the expression:
is used to make diminutives:
is used to make augmentatives
means "to become", "to get":