Before I answer, I would just like to disclaim that I am not familiar with this text at all so if certain things aren't applicable then I apologise. Having said that, I would do aim for paragraph on each factor; failing that, two paragraphs on language and one on both structure and form. I found structure and form generally more difficult to discuss with regards to prose, but a lot easier when analysing verse.
In the language paragraph I would really focus in on, well, the language used. This is rather much like GCSE English Literature, except in more depth. Analyse and unpacking quotes to death, pick out certain words in particular, refer to as many literary techniques as you can. That kind of stuff.
For structure, I would look at the length of sentences and paragraphs and the writer's intent behind those choices. With form, I would talk about how the extract is being told, again referring to why the writer may have decided to do this. That is, the person, the tense, the 'type' of narrative (e.g. flashback, diary entry or maybe a second hand account). You could aim to refer to the reliability of the account; for instance, if it's a first person narrative and it's a diary entry, it might be slightly less accurate than a third person account.
Other tips - as the above user said, different colours are a great idea in the subject as a whole. I would use any random colour to annotate my texts but using a system like the above user advised is a better idea. I don't know which exam board you're with but I was on OCR and this particular assessment objective was the most heavily weighted, so I would advise prioritising it slightly above the others. Besides, making these notes as you go along saves an awful lot of time when it comes to exams. Best of luck with your assignment!