2.) Superman was to square up to TWO Nuclear Men; the one that appeared in the finished film as played by Mark Pillow and another more Bizarro-like Nuclear Man played by Clive Mantle.
3.) Superman was to save a little girl (Reeves' own daughter) from a tornado.
4.) Superman would have stopped a Russian nuclear missile from being launched.
5.) Superman would have taken Jeremy (aka the kid who wrote to Superman about the nuclear threat) into space for a trip above the Earth.
2.) Two Nuclear Men appeared in the original preview screening of Superman IV; with Clive Mantle playing the first Nuclear Man. His scenes involved a showdown with Superman and ended with his death at the climax of the battle. Proving a failure, Superman's nemesis Lex Luthor then created the second Nuclear Man. However due to the reception the film received during previews Clive Mantle's Nuclear Man was cut from the story to streamline the movie.
3.) & 4.) The scene involving the tornado and the Russian missile was also cut from the film, although the scenes did appear in the international release of the movie.
5.) The scene involving Jeremy was cut from the movie but appeared alongside a number of deleted scenes (including Mantle's Nuclear Man) when Superman IV was released on DVD as part of the Ultimate Collector's Edition Boxset.