Hi hysan,
I am a PhD student here at Neuchatel and I recently arrived with my husband (we are both Non-EU) last September 2020. I know the process quite well and I can answer your questions:
It will be way easier if you are married, just FYI.
1. Is she possible to obtain a dependent visa with working permission? What extra step I need to do during the visa application?
- You don't really need to do anything else. Once she will be granted the D visa (needed to enter), she will register in the canton and will get B permit (familial regroupment most likely, sorry my French is not up to speed) and that comes with working rights (permit activite or something).
2. As she is also thinking about whether is it possible to work for one more year to save money before she comes here. Is it possible to apply for a dependent visa after one year I came to Switzerland?
- Yes, you can apply after you've arrived but I heard the process is longer. We applied together (UK embassy as we were both Irish residents at that time) and the process was very fast. Yes, requirements are different but always contact canton beforehand - I find they're always helpful.
3. As my salary is not high, is it possible to support the basic living costs in Lausanne for the two of us?
- Yes, it's possible. We currently live in Neuchatel (I earn the same as you) and I'm still able to put aside at least 500 CHF per month. Of course, we eat at home and I live near the uni but I think very doable actually. Plus, we even get to do the occasional going out when we want to!
As for your language question, she will need to enroll in a French school, finish the whole course, and get the certificate. As we are PhD students and our permit is temporary, the cantons are waiving the need for a FIDE passport (I checked) so any certificate that she has completed the course will be enough.