@profiler already answered to your post, but wouldn't be possible to change your application with your wife as accompanying? That would be so much less troubles and also you would save a lot of money.
Regarding your point #3, does any of you or your wife have any family in Canada? If yes, have them write an invitation letter for your wife. If she is currently working, that's also a plus and I would suggest to apply soon for a visitor visa. Having a job, having a lease, whether in Australia or in her home country, are good to show ties abroad. The fact that she travelled is a plus also. Actually, you being yet abroad might be a plus as well. I would suggest that she tries to apply for a visa before you actually come to Canada.
Thank you for your suggestion. If I want to add her as accompanying member then I will have to apply for a CSQ. I was not sure of time to get CSQ for her. Also I am not sure whether they consider my CSQ application as a new one to calculate point based on the current rule or just give CSQ for my wife based on the fact that I already have CSQ. Those confusions made me decide to sponsor her after my PR.
Regarding your second idea of applying visitor visa for her before I arrive, I considered this option but her relationship with her sister in Canada is not that much good. So I gave up that too.
Please share your view after reading the below info:
The downside of her to get a Canada visitor visa( after I get my PR):
>She is dependent in Australia, so I am the only family tie in here.
> She is a newly graduated student, so she is still searching a job
Positive side:
> I am a student here. Theoretically, my education will complete in Australia on 2020. Thus, she has a dependent visa until 2020. Therefore, I am not going to move permanently to Canada at least until 2019, but go there to complete my PR card process this year. As she is my dependent, my ties with Australia can be considered of her, right?
> She has a good travel history on developed countries
Thank you