They say that the game will be highly editable through text file .xml files. I would suspect them to include a map editor with the game, but im not really sure about including modding software. At first modding will probably have to be done via the text files, but later on I expect the community to create modding software. Which is usual for games like this. Many mods are already being planned for EaW, and if your intereasted you should get involved. Many are also planning on adding episode I - III content. This website: http://www.imperialassault.com/rote/
is a mod that is doing mostly what you are suggesting. If your intereasted in helping them head over to their forums and look under job openings.