Each country and its education sector is assigned with different assessment level to reduced migration risk posed by student from that country. Assessment level is classified into 3 levels. 1 being the lowest risk and 3 being the highest. The assessment level is assessed based on the student last year compliance record, therefore assessment level could be varies from year to year.
Student visa allows you to work up to 40 hours every fortnight and no time restriction during term break. Same applies to your immediate family/dependant.