To me, your prime focus should be the 3 major questions worth 62 marks - precis, comprehension and expansion. If you have command over these 3, expansion in particular, it is going to benefit you in every single paper.
In addition you can cover Direct, Indirect (read rules from some good grammar book), sentence Corrections (Solved Past papers) and Pair of words (Past papers plus Grammar Book or some other resource you have).
Memorizing idioms and vocabulary does not make sense to me, as I have seen people cramming 2500-3000 idioms with the result that not a single of those was asked in the exam. Whether you are able to interpret the meaning of the idiom or the vocabulary (MCQs part) is a function of your English reading since school. I consider the time spent on memorizing meanings of idioms and vocab as time wasted.

As of expansion, ONLY if your English grammar is flawless and you don't make spelling, tenses or punctuation mistakes, you should go ahead with writing 1 page articles. Get them checked by some good English teacher who can mark it for you and rectify grammar mistakes, if any. When you get the green signal, move ahead to writing expansions.
One expansion, one comprehension, and one precis, per week , should do the job.

Regards: