1) The "Zoom" slider is for the small map window. To zoom in on the terrain use the "Alt" slider.
2) Yes
3) Yes you create your own mountains. There are many different ways of doing it. Creating them with the TE, importing actual mountains/land masses, Terragen, or creating them by hand in Paint Shop or Photoshop.
4) They really need to be created each time, but you can create one side, export the elevation bmp and duplicate the areas in your favorite graphics editor.