For copying levels from one to another ... this may not be the best practice but one of the things I did was temporarily create a dependency in my new mod on the old mod, create a new level, choose 'copy from', and then show the inherited levels and copy from the level from an old area. I know there are some issues at the moment with copy levels, but I seemed to have gotten away with it on a couple of occasions. After I got the level I wanted, I removed the project dependency.