1) Looking at the course combo, it is most likely Caulfield due to the Business half of the degree. As for the BITS half, the location varies depending on which major you take (most majors are at Caulfield...one exception is Multimedia which is in Berwick).
2) Depends on if you're into creating/designing IT solutions for business as an analyst or consultant. If your interest lies into the actual programming and building of IT solutions, you're probably best looking at some of the BITS majors or the BSE/BCompSc courses.
If you are interested in the former, though, then there is also the added incentive of a $36,000 IBL scholarship.
3) ?
4) Full on IT course...arguably BSE if you're into lots of coding. It's the longest course (by default, as you have to do an 'honours'/4th year) and, arguably, the most technical. It also qualifies you both as an IT professional and an engineer.
BCompSc would be full on in terms of the maths you'd have to cover, as you'd be dealing with the theories of computing rather than the practicalities of them I'd imagine.
BBIS would be full on due to its course structure in the IBL program (7 subjects in 6 months for 2nd year as opposed to the usual 8 in a whole year).
Depends on what rocks your boat, really.