With the example you gave, it's stating that if you did HSC Chinese Beginners, you are not allowed to take that unit. Your interpretation is correct.
Once you enrol, you can access MyAdmin with your unikey so you can change things immediately.
That being said, a watch is something you can "blow" your money on as they are timeless accessories. Whether you're 15 or 95, it will still serve its purpose (with due maintenance) regardless of how you age.
If you're doing honours, that's a big plus because it gives you time to figure out that niche you're looking for and do an in-depth study of it. Considering that, it's a great way to open doors.
Also a Commerce degree is flexible due to the variety of majors you can choose from.
ECMT1010 isn't really like anything you've done in school (3U and 4U included) but it does use a variety of statistical concepts so I don't think there's much to worry about.
Conceptually, it's different to the areas you would associate with high school mathematics so even those well versed in...