>> #1 what is the significance of the first colum ?
The first column is the voxel index number.
>> #2 Why in the second study p,q values do not change at all?
As the p-value listed in the 2nd study does not change much, the algorithm simply renders the same q value, thus the same z-score. Go to page 2 of 3dFDR manual, you will see how the algorithm works.
Gang