The official VCAA line is: Methods 1 & 2 is a prerequisite and Methods 3 & 4 is a corequisite. The only required knowledge from Specialist 1 & 2 is from two areas of study: geometry and trigonometry in the plane (transversals and parallel lines; solving triangles using trigonometry; circle theorems) and number systems (arithmetic of natural, whole, rational, real and complex numbers; absolute value of a real number).
As for topics that you would need to study for, that is something to discuss with your teacher, because it depends on how they run the course. However, I think it would be beneficial to learn the basics of:
- Vectors
- Forces and statics
- Trigonometric identities involving reciprocal functions and compound angles
- Parametric equations
- Sampling distributions and random variables