You can get more info in the other subforum:
http://forum.lowyat.net/EducationEssentials

1. Difference is basically how the course is. Some is 100% exam (e.g. A-levels), while some is 50/50 on exams and course work (e.g. Australian ones). There's also the length of the course. I'm sure you know government form 6 is a 2 year long thing, A-level is usually 1.5 years, but can be 1 year if you are smart enough to take the crash course. Australian matriculations are usually 1 year, some January intake, some March intake but ends at the same time. Which pre-u you wanna take will depend on which university you plan to go to as well. Make sure the university you wanna go to will accept the pre-u. A-levels is always a safe choice to go with if you do not have any specific choice yet. For example, MUFY (Monash Uni Foundation Year) is the pre-u course for students that wants to get into Monash Uni.

2. For business related course, you can always take business admin or something like that first. Most degree in business will require you to take all the basic business subjects in the first year before you choose your major in the second year. Engineering is a whole different thing from business. Talk to some of your seniors about their courses and see if what they learn is what you are expecting. Go check out the link I gave earlier as well.

Then go visit those universities, go to their websites or go to their booth during education fairs. I took foundation in arts in HELP and went on to Psychology for my degree. The foundation program in HELP is pretty decent, though I can't make a comparison with other unis' foundation programs (Since i never took them, obviously). One of the core subject involves learning how to use core computer programmes and you are required to attend a training camp in your foundation year (good exposure).