Answer your last question first, foundation course will take a year. Usually start at February till November.
About the first part of the question, It's really hard to say and it's really depends on your own result. Normally if you want to study foundation course, you will need at least a full cert (If you using Hong Kong as a standard, this is base on my own exp few years back) and you need to have at least 5 to 5.5 for IELTS.
As I talk to my own friend who study VCE, the thing I study is about the same as VCE. In fact personally I think VCE is more easier then foundation. Because usually the teacher/lecturer in foundation can be very harsh in term of marking the exam