Send in your acceptance and whatever other forms you have. Your logon details are sent to you and then you can apply for accommodation. Once the final ballot for accomodation has been done you can check if you were accepted into accomodation, at which point there will be a room fee listing and a date that you have to pay by and all that. The fees you have to pay to be considered in the ballot are things like your IT levy (I think) and the fees for O-Week. If you're going self catered accomodation, just remember that in O-Week you only need food for lunches as you get dining hall food for brekkie and dinner (covered by the fees you pay now).
As for enrolment...appart from kiddies doing a B.Arts I'm pretty sure you are automatically enrolled for at least your first semester of subjects, but if not, it gets fixed up during O-Week. The last day to change your enrolment without incurring any hecs isn't till the end of March so you have plenty of time to muck around with that.
As for your timetable, details from the uni will tell you that your timetable will be up approx. a month before classes. In reality, it'll probably turn up about a week or two before. It's your responsibility to check that though so keep an eye on it. If it's not up before you go for O-Week then they'll announce during the week when timetables have gone up.
With my.csu - just make sure that when you sign in, on the page it takes you to there is 2 tabs at the top of the page. One is 'My Channel' and one is 'Student Services'. Make sure you're on the 'my channel' one. I can't access the forums from student services either but if it's on my channel then it always lets me through...Otherwise just wait till you get to uni and talk to someone from IT. You won't be missing much on the forums as people are generally fairly quiet in the holidays...
Woah! Long post