Umm, you do NOT need to know the phonetic alphabet at all, they will never ask you for it.. Only use it if you want to see better by writing in examples for the essay at the END of year. Do NOT bother with it now, the most pointless study you could do haha ><
With the metalanguage
Morphology, lexicology - parts of speech (verb, noun, etc..), suffixation types
phonology - how to define various terms, know broad, cultivated, general phonological differences
syntax - sentence structure, sentence type (these are different and must be known!) about subordinate/main clauses, what a clause/sentence/phrase is
Know these first, the others semantics/discourse are far more relevant to unit 4, though still important in unit 3 you dont need to know them right away
im sure im missing heaps, but there's a start - know the essentials/basics first!