1) I don't know how the registrar gave permission for society to be formed as every member is owner of the plot and pays his own tax and stuff.I think Associate members should be formed. Please sugge
You have not informed that the society is registered or not, if it is registered then the formalities meant for the same including submission of membership list along with their signatures to be submitted to the cooperative registrar.
2)As there is only one inlet for my plot and i have connected the new tank to already fitted tank can society ask me to remove it or charge me for it?
A formal permission from society may have obtained or atleast now the society's orders may be complied.
3)If am charged for extra tanks as its unfair towards other member having one tank(according to society) Is it not unfair towards me as permanent members use more water should they and one using for commercial reason be charged rather than me?
Reasonable argument, you can put if before the meeting.
4) What right does society have on my plot as I am the owner of it, do i have to inform it for every changes in my house or informing the gram panchayat/concerned office is enough?
Once a society is formed you may have to abide by the rules and bye laws of the society
5)If I don't become a Member of this society can they stop water for my plot as I have paid for the well as well.
They have no rights to disconnect water supply because it is part of basic and essential amenity.
All the other points can be taken up effectively only when you become a member and actively participate in the general or any other special meetings of the society.