Statistics are especially useful for essay responses and some short answers, but for multiple choice it's pretty pointless (unless if your examiner is cruel enough to throw in a statistics question, but at that point I'd argue that it's not even an economics question so much as it is a memory quiz). I didn't use statistics at all in my final HSC exam (and very scarcely used it throughout my internals) and still managed a Band 6. Though generally, if you can throw in a couple of statistics in your response, you should. Topic 1 and the start of topic 2 doesn't have that many anyway.
20 marks short answer typically means two short answer questions worth 10 marks each, but has three to four parts to each. It's pretty typical for Topic 1 examinations to test you on economic development; what it means, strategies of how nations can improve their economic development, analysing the effectiveness of Australia's (or another economy's) pursuit of economic development. Make sure you're familiar with how globalisation is perpetuated, and a general idea of the impacts it has on individual economics. Regarding the second topic, they're likely to test you regarding the Australian economy, such as the direction and composition of our trade flows and how they've changed over time, and the balance of payments (as calculations in the multiple choice and the discussing of its significance in the short answers).
It's also common for internal examiners to take HSC questions of the last few years.
Short answer questions which are relevant to you from the last few year's worth of HSC exams:
- 2015 Question 24 (globalisation)
- 2014 Question 22 (interest rates + balance of payments, ignore if you haven't learnt interest rates)
- 2013 Question 22 (economic growth)
- 2013 Question 23 (current account deficit)
- 2011 Question 21 (globalisation)
- 2011 Question 22 (balance of payments)
- 2010 Question 21 (Australia in the global economy)
- 2010 Question 22 (globalisation)
- 2010 Question 24 (exchange rates)
As for multiple choice questions, Board of Studies did have an online multiple choice generator for Economics, but it is currently down as I'm writing this post. Perhaps you can try it later.
Good luck!