Right-click on the stat results > File > View file contents, then look for the StatClusters structure, it contains the clusters informations reported by FieldTrip. Look at the FieldTrip documentation for help with these values.
The significance values obtained for each cluster are the same over the entire cluster. If you want the corresponding MNI coordinates, you could find the significant vertices (from pmap field), then average the positions of the vertices in a cluster. You can get the positions from the cortex file, then convert the coordinates to MNI space:
http://neuroimage.usc.edu/brainstorm/Tutorials/ChannelFile#On_the_hard_drive
http://neuroimage.usc.edu/brainstorm/Tutorials/Scouts#On_the_hard_drive
http://neuroimage.usc.edu/brainstorm/Tutorials/Statistics#On_the_hard_drive