G'day, whilst I don't usually use this feature I'll try just this once
1. UNSW B Comm is pretty good but each university has different strengths. If I could go back and do it again, I would probably pick UTS because it's more convenient for cadetships. However I did have a lot of friends at UNSW which worked in it's favour.
2. Yes. Transferring internally is based on your WAM (weighted average mark) of your uni subjects as well as your UAI. Any more detail than that you'll need to ask someone who's actually transferred.
3. Yes. Workload isn't too bad- nowadays it's even more flexible with the 1 day off per week to attend uni making it a VERY easy balance if doing part time.
4. I had the cadetship and TBH, economics in uni is considerably harder than high school. It's much more statistics/formulae/maths driven which I don't really enjoy.