Dv has to be proven before granted ?

[1] Does the burden to prove the allegation lies on the wife or husband ?

Wife.

[2] If wife fails to prove the allegations, or husband can disprove most of the accusations, will the maintenance still be granted ?

Not granted.

[3] What is the implication if she willfully left the matrimonial home.

If it is proved voluntarily without any reason she left the m. house, she will not get any relief.  If she proves that she is forced to leave matrimonial home, then she will get the relief.

[4] Can she still claim maintenance she was earling high salary before marriage (80K pm), and still capable of job, and chooses not to do a job.

What she is doing right now is the material.

[5] How much old / new salary slip is taken into account while calculating maintenance ? (I have heard it's last 6 months income from all sources) From the day case filed or granted ? And does the husband's profit/loss from stocks have to disclosed with salary income and adjusted to the amount to calculate maintenance ?

There is no hard and fast rule.  In Delhi, last three  years details are generally sought.
 

the allegations kept on you has to be proved with evidences and if not then the allegations are base less and about her maintenance court will grant after seening all the aspects as why she left and what reconciliation steps you have taken to bring her back and reason about her leaving

and about salary slip if court asks then you have to submit payslip and if the previous is more and present is less then there should be a pefect answer to stabilise your salary slips

a case of DV has to be made out in the application itself.

Bombay High Court
Rajiv Hari Om Bhatia @ Akshay Kumar vs Anita Advani And Anr on 9 April, 2015
Bench: M.L. Tahaliyani

15. In view thereof, what is necessary to be examined is as to whether learned Magistrate was
justified in issuing show cause notice to the Petitioners on the application made by Respondent
No.1. It is not necessary to be stated here that notice could have been issued only when the
application discloses a prima facie case for entertaining application under section 12 of the Act.

18. It is thus, obvious that the Applicant /Respondent No.1 was under obligation to prima facie
demonstrate that she had relationship with the deceased in the nature of marriage. If that was
lacking in the application, learned Magistrate could not have issued notices to the petitioners. In my
considered opinion the Respondent No.1 has failed to show from her application that she had
relationship with the deceased in the nature of marriage. I have therefore, came to the conclusion
that no case was made out for issuing notices to the Petitioners