Hi there

I'd recommend having a sit down with your English teacher at school (or another teacher from the English department) to revise structure. They should be able to help you work out a system that works best for you!
I graduated 2 years ago so there's probably people who can give better feedback than me, but the key thing you have to focus on when doing language analysis is analysing the effect that the author's language has on the reader and explaining it. I have a feeling that you might fall into the trap of summarising (as many students do!), or list what an effect might be, but you fail to go into depth about it.
I found that it really helped me to always be asking myself "how does this impact the reader? what does it make them think/feel/do? why?" as I was reading an article. I reckon this helps you move away from focusing on language techniques. Then, when you're writing, keep on asking yourself "why?" and if you feel you can elaborate further, do so, and if you feel like you've explained it enough, then you're good!
For example, from your paragraph:
"This will cause the students to not be angry with the writer but be calm due to the writer expressing the opinion of both sides."You've definitely touched on the why, but you can elaborate further.
Why would the writer expressing the opinion of both sides cause the students to not be angry?
When I was refining my approach to language analysis, I started out by practicing annotating and analysing heaps of articles - I didn't even really write that many paragraphs (just a few, to get a feel for my structure). Then, once I had that initial analysis down pat, I moved on to refining my writing. Obviously different things work for different people, but I found that doing this really helped speed me up in timed situations without compromising quality.

As for building vocab, read! Start reading the newspaper, read other students' language analyses, and just keep on practicing your writing. When you get a draft back, read it, then figure out if you can replace some of your words with other words, and if you can rearrange your sentences. I'd often go back through drafts and cross out whole sentences, then rewrite my pararaphs.
Hope this has helped - I'm a bit out of touch with VCE English, but I always found it to be one of my more enjoyable, and stronger subjects, and some of the stuff you learn never really leaves you