I can only speak for Melbourne Centre, but there isn't really a typical roster unfortunately. They vary not only from group to group, but also within the group, as well as at different times of the year for some. Count on working more weekends than not though. For example a simple 4 on 2 off roster will give you one complete weekend (Sat and Sun) off and 2 half weekends (Sat or Sun) in 7 weeks.
Particular runs or patterns of shifts can be particularly family unfriendly (or so I hear
). An evening shift for example may have you waking up after the kids have gone to school, and getting home after they have gone to bed, which may wear a bit thin after 5 in a row. Or you may be getting home after a night shift at 7am on a Saturday and trying to sleep! On the other hand, most shifts are morning, afternoon or night, so even if you a working the weekend you might not loose it all.
Another unpublicised "feature" is rec leave (holidays). Only a certain number of people in each group can be on leave at once, so to facilitate this all leave must be booked 14 months in advance. Booking time of for events that are arranged less than 14 months in advance can involve some guesswork and luck.
I'm not trying to put you off (personally I prefer shift work and couldn't cope with 9-5) but it is a 24/365 job, and you are paid to work shifts.
Someone has probably already suggested this, but ring up and arrange to visit the centre. Not only will you get a bit of an appreciation for the job, but you can see some rosters and get a feel on the working environment and general morale of the place (unless you get stuck with the group grump, most have at least one
)