Being a Java programmer myself, I can recommend using Eclipse as IDE when you program Java. It is free and very powerful. Sun's Netbeans is free and should be great too, but I don't have experience with that IDE.
Not that much, and with good reason. I've done some research and I might be walking too fast. :blushing:
It appears there is a fundamental difference as the base of Hammer is brushes and of Blender faces. I don't understand it fully myself, and the info is quite sparse, so just ignore all my "want a Blender script!" requests for the moment