1) As your wife is earning sufficiently she is not entitled for any maintenance. Alimony depends on several factors including dissection of the presiding judge. You need to bring proof of her earning before the court.
2) Let me quote Sec.24 HMA for you. Section 24 in The Hindu Marriage Act, 1955
24 Maintenance pendente lite and expenses of proceedings. ?Where in any proceeding under this Act it appears to the court that either the wife or the husband, as the case may be, has no independent income sufficient for her or his support and the necessary expenses of the proceeding, it may, on the application of the wife or the husband, order the respondent to pay to the petitioner the expenses of the proceeding, and monthly during the proceeding such sum as, having regard to the petitioner's own income and the income of the respondent, it may seem to the court to be reasonable: 54 [Provided that the application for the payment of the expenses of the proceeding and such monthly sum during the proceeding, shall, as far as possible, be disposed of within sixty days from the date of service of notice on the wife or the husband, as the case may be.]
As evident the section provides for reliefs of litigation expenses and maintenance the spouse during the pendency of the portion. You need to reply and appropriately defend the application.
3) There's no hard and fast rule around maintenance awarded. It will depend on several factors like your income, her income, the standard of life she had while she lived with you, how long she has been working etc. As in your case she earns 16000/-and has dependents including a child she cannot Alain a huge alimony and maintenance. Your affordability taking into consideration your present liabilities liabilities the court can order an amount as alimony using its discretion besides.