Hey underthesun,
I was planning to answer this and had an answer all written down just before my house had a power failure, so here goes again
(that was before you sent me a pm, mind you
)
As laz said, Maths 1A and 1B are compulsory for UNSW science/eng ppl. It's not too hard, just make sure you don't fall too far behind (some people were trying to learn the whole course in 2 weeks, and that's a hard ask
)
Electives? I can tell you about the ones I know...
Discrete mathematics: Comp sci does this as compulsory first year, everyone else does it second year. Quite interesting, about modulo arithmetic, set theory, "formalising" what you intuitively know about subjects. Recommended, as it's quite logic-based.
Second year courses: You get to choose stuff like "several variable calculus" and "linear algebra", as well as "analysis". it gets a lot harder than high school maths obviously because you build on that stuff, but since quite a lot of people doing science or engineering do those courses (esp several variable I think) then they aren't overly difficult, esp if you take the normal as opposed to the advanced stream (don't worry about that for the time being for second year courses, you'll know which one you want to take at that time
) Umm... yeah. I guess it's the same as any other course, a bit more logic involved, which means that you actually have to understand the stuff and regurgitation works a lot less well.
Third year courses: I don't think you get a chance to do it, but if you do end up doing pure maths it's interesting
In summary: First and second year maths were designed that ppl from other courses can take it without too much trouble, and it does move up a level but nothing you can't handle (considering you've done ok in 4 unit, a little bit of effort and you can probably keep up).