I'm not too certain about the structure (still working on it myself), but I hope this helps a bit:
Explaining individuals' options to influence change - formal (explain the VLRC) and informal (explain petitions, demonstrations and the media)Formal pressure is from within the law-making body through ministers, cabinet, parliamentary committees, and law-reform bodies like the VLRC, whose job it is to research areas of law that may require change and to make recommendations to the government for changes.
Informal pressure comes from those outside the formal structure of the law-making process. Individuals and groups may utilise petitions (a written request to the government for action in relation to legislation that may be considered outdated or unjust), demonstrations (a group of individuals expressing public desire for change, usually in a prominent place like the steps of parliament, and usually disruptive), lobbying MPs, social media (like videos, links to ePetitions - an example of a group which uses social media effectively is GetUp!) and traditional media (letters to the editor and opinion pieces in the newspaper, talk-back radio, advertisements on TV, etc) to persuade parliament to make changes to the law.
The purpose of the second readingThe second reading is where the Minister or Private Member gives their Second Reading speech, and copies of the Bill (complete with explanatory notes) are given to all the members. It is also debated in principle, but it is not debated clause-by-clause (this comes in the "consideration in detail" stage).
In the Victorian Parliament, the bill is compared against the Charter of Human Rights and Responsibilities Act 2006, and any inconsistences are amended.
Representative governmentRepresentative government is a government that makes laws pertaining to the views and values of the majority, and is elected to represent the people. It is acquired through regular elections, as any government which does not uphold the wishes of the majority is likely to be voted out of office at the next election.
Responsible governmentResponsible government is concerned with the ministers. Ministers are considered accountable for their actions, and are also answerable to parliament (and therefore the people) for both their actions and the actions of their department. They are questioned in parliament by other members during question time. If ministers do not act with honesty and integrity, they will be forced to resign.
For the separation of powers, you basically need to mention that it prevents abuse of power, and describe what legislative, executive, and judicial powers are, as well as who enforces them. Remember to mention that they are all kept separate from each other in theory and that there should not be any interference, but that in Australia, there is an overlap between executive and legislative powers (due to the ministers). The only power that is kept entirely separate is the judicial.
Not sure about effectiveness of parliament, since we're not up to that bit yet. I don't really get how a bill is made either...so I left most of that. JCurmi's response pretty much sums up what I would write for the "reasons for change" part.
If it was worth more marks, you could provide an example like how the Summary Offences & Control of Weapons Act Amendment Act (2009) gave police the power to publicly search individuals for weapons.