Re: Teaching overseas
I believe its not so much the 'degree' thats recognised, more the being registered as an Australian teacher. I was looking at studying education in New Zealand and then coming back to Australia, or even going over to Europe, after my degree. They informed me that it was not a problem with the qualification crossing over but there is a certain probationary period that must be fulfilled in the country where you received your degree (maybe two years teaching?). I would imagine that Australia is similar, ie. you do your course, teach for the period of time then you are a fully registered/qualified teacher and are able to work in countries that accept this qualification. What I was asking after was Secondary education though - so maybe look into Primary some more.
Another point, all qualifications in Australia, while some carrying more "prestige" than others, are the same. All universities (to my knowledge) have to teach to certain guidelines that validate an Australian degree. So whether you were to do something at ACU or USYD the qualification would be worth the same - although there obviously may be difference in lecturer quality, subjects etc.
I believe you can get those certificates for teaching English all around - my mother was looking at doing something like that in a weekend course for around $500. You can always do that if you want.
Good luck.