I think you can stop the infoWindow from displaying if you call dojo.stopEvent()right after your onClick that enables the editToolbar
dojo.forEach(layers, function(layer) {
      dojo.connect(layer, "onClick", function(evt) {
            dojo.stopEvent(evt);
            editToolbar.activate(esri.toolbars.Edit.EDIT_VERTICES , evt.graphic);
      });
});
ive also had issues with infoWindow showing when you click a new point with template picker over existing featLayer graphics. That issue was fixed using featLayer.disableMouseEvents(); after the template was selected
dojo.connect(templatePicker, "onSelectionChange", function() {
      if(templatePicker.getSelected()){
            //template selected disable non-editable featLayers onClick event
            dojo.forEach(nonEditFeatLayers, function(layer){
                    layer.disableMouseEvents();
            });
      }
       else{
             //template selection cleared, enable onClick
            dojo.forEach(nonEditFeatLayers, function(layer){
                    layer.enableMouseEvents();
            });
        }
});