1) - Try asking your TAFE Student Services, if not, call these people:
http://studyassist.gov.au/sites/studyassist/helpfulresources/pages/contact-us
Since they're the government organisation that organise all the HECS-DEBT/HELP.
2) - It depends I would assume, online courses as far as I know can be finished as soon as you possibly can. Face to Face I would imagine would be a duration of one year. There is lots of Diploma's in Financial Planning and the like, some viewed upon better than others.
Do you know exactly or likely what you'd like to do in the finance industry?
If you're half way through your current diploma, it would be a waste of 6 months or so if you just dropped out. Bare in mind, commerce and finance are quite similar and you'll probably over-lapse some knowledge which you can use from your commerce diploma, in your finance diploma. - As you said, reading financial statements etc.
I wouldn't expect a finance diploma to go to in depth, I could be wrong. Instead I think they'll touch over lots and perhaps focus on a couple of key areas.
P.S - By what I hear and read, you can basically get a diploma to become a financial planner out of a cereal box these days. Perhaps the reason people have lost faith in them, since the quality as dropped off - apparently so anyway. Take a look at AMP's Horizon Academy, amongst other financial planning diplomas.