Honestly, with all that research and experience, you are going into law school far more informed than I would say 99% of first year law students.
People in the US regret it because:
1) they do not have HECS over there; instead, they must borrow exorbitant amounts of money to pay off their school fees, which carry interest and must be repaid regardless of how much you earn (unlike HECS debts); and
2) the lawyer job market in the US is atrocious, meaning lots of graduates can't actually get the income they need to pay off those loans (
this should give you a rough idea)
The job market in Australia is nowhere near as bad, although it is obviously still challenging particularly if you are aiming to go into a top or mid tier firm (like Corrs).
Stress: yeah, it's stressful, but it's not as bad as it sounds particularly if you're only reading about US experience. Their law schools sound far more stressful than Australian ones. Workload can be high if you are aiming for top marks but it's also possible to cruise through semester doing nothing (because most law subjects do not have assessments throughout semester), cram everything in the last week before exams and do relatively well (do not recommend this though, it's playing Russian roulette with your degree).
Depression: lawyers have one of the highest suicide rates I believe (after dentists). This I assume primarily stems from the lack of work/life balance that comes with being a high-flying lawyer, but that's not the only career path you can take. If you are talking about depression in law school I honestly don't know what the statistics are, but Monash has some good support systems for that.
Debt: HECS is amazing. Government pays some of your fees and the rest is on an interest-free loan (subject to inflation only) which you only pay back after you reach a certain level of income (around $50k/year from the top of my head). You really don't need to worry about this. Australian university students are some of the luckiest in the world.
Jobs: considering that every university in Victoria offers a law degree, you can imagine how many law graduates there are every year. So yes, competition for internships and junior lawyer jobs is quite intense. But a law degree also opens up pathways to other careers (see the link in my signature for some ideas).
Feel free to ask more questions!