Hello,
1) There's no specific time limit set to file or produce evidence. However, if for no valid reason the case is being protracted you can move a petition to the same court highlighting the behaviour of the complainant.
2) No limitation for paying maintenance if an interim order is passed by the court.
3) Of you want your wife to come back and resume get marriage with you, you can file for Restitution of Conjugal Rights petition. It is a good ploy to bring out some accountability from her.
4)498 A is criminal case and attracts rigourous punishment. DV case is a quasi criminal case beaming meaning it has criminal element as well as civil as it pertains to family.