The kids are fine to ski at any age, I was 2 and skiing. Look at their learn to ski programs for the kids.

The Victorian ski fields are approx 2-3 hours from Melbourne and there are a variety of them around, I'm going to be sampling this year, might do a weekend drive to the NSW fields too.

Mid week is always better, just stay away from school holiday times, not only with families, but school ski trips.