I thought about putting up some hints and tipps for easy / fast mapping with the Torque-Editor and Hammer. Mainly for me to remember the stuff:

1. Create a batch file to add images to a certain .WAD-file
   I have a batch-file that adds all images in a folder to a .WAD-file called let's say TEST.WAD. In hammer I only use this .WAD-file for my textures. Whenever I have new images to be added to the .WAD, I copy the images to the folder and run the batch - voila, here I go with my new textures available in Hammer. (Hammer has to be "stopped" before running the batch, else the batch cannot write to the .WAD-file.
2. "Auto-Update" interiors
   Hammer.Exe and the Torque.Exe can be run simultaneously! There's no need to restart the complete Torque.Exe if you make changes to an interior in Hammer. Just restart the mission! As long as your interior doesn't change in size it will be available as soon as the mission has been reloaded.
3. Empty squares
   Looks like empty squares remain "visible" if the surrounding terrain has the same height.
   Here's a screenshot where the selected squares are already set to EMPTY and the surrounding terrain has the same height.

   
   Example1

   Here's the same scenery from a different point of view:

   
   Example2

   After having altered the height of the empty squares, they become visible (this is the same point of view as in Example1).

   
   Example3