First thing first, you need to find out if you are an "employee", not in the normal sense, but legal sense.
This directly affect the copyright issue, outside your "work hours". If you need their consent on take on other clients, that would be iffy. There are a number of things a court would look at to determine this. You may think you are a consultant(thus tools you develop during the course is yours, so long it is outside "contracted hours"), the court may not think it this way. -- http://mail.python.org/mailman/listinfo/python-list
