@Sheena1987 This is by no means an exhaustive analysis of your query since you did not provide the details of your intended course and your background (academic qualifications and work experience).
Student visa to PR, imho is possible if:
you take a course that would provide you with skill(s) that Australia is in need of (Skilled Migration Pathway - 189, 190, 489/491)
you find a employer who will be willing to sponsor your visa (Temporary Skill Shortage - 482 or Employer Nomination Scheme - 186)
While on student visa you and your dependent(s) are allowed to work for 20 hours a week or 40 hours per fortnight, so full time working hours is a no no otherwise your visa may be cancelled and may cause a record against your future plans.
Am not sure with taxis but for Uber, it is required that the driver has held an unrestricted (Class C) license for at least one (1) year.
Regarding "study now pay later" schemes of some agencies, I am aware of many discussions about this among nurses but not with other occupations. I think meron din pero dati usong-uso to dahil
I once considered the option pero expectedly mataas masyado ang interest kaya I found other means na lang. At any rate, there's no harm naman in asking around.
Best wishes on your Australian journey.