Hey, yeah I was wondering about enrolment too, particularly because all the UNSW's are whinging about theirs
As for the majors question, I emailed someone in the arts faculty at the uni the other day and they just replied to me, it's probably relevant to your question (but not to my original one, ironically...)
"You will not need to be completely certain about your majors as you will have a year to decide on that. You should have a shortlist, however, of possible majors organised as the units you will undertake in your first year will determine what pre-requisites you have completed. These pre-requisites are required for doing senior units, which are the requirement for majors. You will need to select your subjects for 2011 on enrolment day, so please have them ready when you come in to enrol."
Yeah see I think that's just for normal arts degrees, so that would be the case for you. (well, I know you're doing media/comm, but it would still apply I think.) Because I'm doing adv honours though, we don't have to do the pre-requisite junior subjects because we skip straight to second year. That's why I was asking the question about deciding majors straight away but he doesn't seem to have answered that for my case. :/