Hey Snow Leopard!
I completed 1/2 HHD and am doing 3/4 at the moment, so I'll try to answer your questions as best as I can
What is HHD about? To put it simply, in 1/2, there is a focus on the health and wellbeing of population groups in Australia, particularly Australian youth, a bit of nutrition, as well as human development, in the context of how a person's life starts at conception and goes all the way until late adulthood. In 3/4, there's still some of that health and wellbeing stuff, nutrition, models of health, how health has changed over time and health in population groups, as well as global health - looking at health around the world and how different factors influence it. I just said the word health a lot there. Haven't started Unit 4 yet, so can't exactly give a great description! You may to wish to look at
these helpful HHD resources written by some ANers who are passionate about HHD and scored highly for more information about the subject and consult the study design.
What do you need to do in order to do well in SACs?This is really general advice, but overall, you need to stay on top of the work and be consistent with revision. HHD is a content heavy subject (maybe not as content heavy as bio and psych) so adequate time to revise is very important IMO. There are some parts of the course that are applied to each unit - for instance, you will have to link different concepts to the dimensions of health and wellbeing and health status indicators, so it's important to know these very well. There are some things you might need to know almost word for word (think definitions) and some that you don't need to memorise, but have a solid understanding of to write about in extended response questions. The subject has questions that come up in exams in similar forms, such as how a concept promotes health outcomes. Alike every subject, passion or at least a little bit of enjoyment for HHD can motivate you to do well in SACs.
What are SACs like in terms of structure?All questions are short answer. Be prepared for a lot of writing! There are some questions that are worth two marks (for example, "identify" questions) all the way to extended response questions (so you're looking at 8-10 mark questions). VCAA have moved towards including a lot more higher order thinking questions into HHD exams, so you'll see fewer of those "identify" questions and more "analyse" or "evaluate" or "explain" types of questions pop up.
How much work do you need to put in to get good results in it? (How much work would you need to do to get a 45+ score raw)?I don't think I'm too qualified to answer this one, but the amount of work to put in for a certain score is quite a tricky thing to answer. There are so many factors that influence study scores anyway, and the results you get can be influenced by your personal strengths and weaknesses. Some people treat HHD as a bludge subject, and experience different outcomes. To do less work in this subject and maximise your results, I guess finding study strategies that work for you can save you time. There's a general consensus that HHD is an "easy" subject, but if you want to do well, you have to put in some effort and solid work.
Hope this helps you out a bit (and hope you pick HHD - one of the best subjects VCE has to offer
)