Yes, however, I think the foundation-the study skills one build from year 11 is essential for success in year 12, I think it is important to not diminish the results of year 11 since it is often a good indication of how one would progress through year 12 provided they maintain a similar attitude to study and have consistent study habits.
Somewhat true. My ranks for year 11 suggested I was going to get low-mid 80s mostly due to me doing very little but just focusing in year 12, I got a mid 90s ATAR. The most important thing for the HSC I've noticed is consistency and iteration; do your work, complete your homework, revise your done work and NEVER fall behind in subjects that require problem solving even if you have to stay up late/skip leisure activities (this kicked me in the butt for maths). IMO English is easy to ace if you write your essays early in the year and make concise improvements/changes throughout the year. Although, at the end English is idiotic in the way the marking can largely be left to interpretation - there is however a standard which can somewhat ensure you a band 6.
Subjects such as Business Studies and other content-based subjects are super easy. I did not even consistently keep up to any of the homework/content in biz but nearing the HSC rushed and was able to finish the biz book from start to finish in a bit more than 1.5 weeks (got 94 in the hsc). If you're able to be the least bit consistent with these type of subjects you'll no doubt get 90+.
Another important advice is to not push yourselves too much in the early days - maintain consistency but don't go overboard studying more than you're able to (unless you know for sure you can handle it). You'll find yourself mentally exhausted and disorganised nearing the HSC.
P.S. year 11s should stop procrastinating by looking at your marks as they mean jack shit. sorry.