I had talk with my manager. He told me to "ensure everything mention in requirement document should covered in SRS" thats all.
Regarding other questions:
The state of the SRS document : Is it complete?  If no, to whom will you provide the feedback?  Who will give the sign-off?
I have to give feedback to my manager only. He is going to sign-off on SRS.I think as decision maker.
Who are the stakeholders: the SRS document should contain this already but you need to find out who the key players are: end-users, project sponsor, decision makers, etc.
Marketing person and my manager ( as I asked him). The SRS document doesn't contain about this.
How much money is the company willing to spend on enhancements?  Is there a limit? 
According to him , there will be no need of enhancements of the system.System is covering all the aspects of our requirement. So there is no question of enhancements budget.
any suggestion please.!!!!!!