I haven't logged in here for ages (You last visited: 20 Dec 2006 at 9:09 AM) but I do know that there are similar topics such as this.
Anyways, its good that you're thinking early ;p
I currently do Design Computering (first year) at USyd. I only got 82.4 in UAI so I guess I entered through portfolio (they accept it if you're in the 80-85 mark). Those who get into accepted in is only like 40 people + probably 5 from portfolio.
Just to give you all the basic info: it's 3 years, 1st year is a set course (so you don't have to choose/ can't choose electives), the rest of the 2 years you get to pick 12 units of study (usually 2 subjects of anything you want). It's 18 hours shedule but you don't have to attend everything ;p The first term, we have to do database management (SQL, XML, UML and Express-G) - you have to code and stuff (not the best subject..); another is understanding design and cognition which is basically getting to know the basis (function, structure, behaviour) - be prepared to take on analysis of chairs (though the best thing is that we get alot of guest lecturers - like a guy from Animal Logic who talked about behind the scenes in design in Happy Feet ;p); the last one is practical work - this is the best; its split up into all the practical work - like learning Photoshop and Illustrator and then you have studio work ^^ For most of the this term, we spent time making our own comic (due tmr). And half the times its 'self-directed work' so you didn't have to come to uni.
Next term, we're doing 3d modeling (and unfortunately the theory of multimedia while we're at it).
Oh yea, and there's NO exams (unless you choose an elective like Bio which has exams..) so we get like holidays 2 weeks earlier than the rest of the ppl ;p
English isn't much of a problem actually; a friend of mine is an international student and her english is like esl? But she's still getting credit scores.
There are actually plenty of jobs avaliable, as Design Computing students come out as anything you want to be because of the flexibility in electives. From game designers, to animators, to web developers - could be consultants, database management, marketing etc. It's just that they pay for low end isn't that great (maybe 20-40k a year), however if your on high end could get (80-100k).
I believe BA Design in Architecture is just the basis for continuing on to do BA Architecture. And it really would depend on what you like.
If you still want to keep your options open, I suggest you go for BA Science and Technology - 1 science, 1 maths, 1 or 2 electives - which still allows you to do design computing stuff if you go for the 'design stream'.