Make sure to include these as a minimum:
Present/past (imperfect, perfect and maybe pluperfect)/future (simple and near if you can)/maybe conditional tenses
Opinions that are JUSTIFIED (e.g. je trouve que la nourriture dans la cantine est dégoutante PARCE QUE nous devons manger les haricots verts tous les jours)
Some idioms if you can find some as has been mentioned
ADJECTIVES
Complex phrases e.g. qui/que, ce qui/ce que, il faut, je décide de + Infinitive, une fois + past participle, après avoir/être + pp, avant de + Infin
Conjunctions e.g. Cependant, mais
Time phrases e.g. Puis, ensuite, hier, le lendemain
I would also highly recommend structuring your answer with paragraphs along the lines of the bullet points in the question. So one paragraph answers each bullet point and try to write equal amounts for each one. This makes it much easier for the examiner to mark and for them to give you the communication marks for answering the question. YOU MUST ANSWER EVERY THING THE QUESTION ASKS!
If you're aiming for grade 9 then I would certainly recommend including some much more advanced grammar structures. E.g.
Conditional perfect
Future perfect
Passive in all tenses
Present and perfect subjunctives
Causative (e.g. Mes parents me font laver la voiture - my parents make me wash the car)
Expletive ne + subjunctive (this is advanced! PM me if you're interested).
The advantage of these is that they will impress an examiner and maybe make them more likely to give you higher marks. But I wouldn't worry too much about these if you haven't met them. I think you can get full marks just by answering the question and making everything as accurate as possible. The best people will be making very few errors, if any, in their writing and that's who the grade 9s are for.
Je te souhaite bonne chance avec tes examens!