For most people the way custom ROMs work is that you find one which has what you want. As SiempreTuna says, you can remove stuff once rooted even without a custom ROM.
What is it about Touchwiz you dislike? The launcher can easily be changed, and doesn't even require root. You may be able to do something about some of the other look and feel aspects (menus, icons, colour schemes etc) with a custom ROM or the deeper theming that root allows. But if you want those features you name you will have to use a Touchwiz-based ROM, since they will rely on Samsung's framework rather than being stand-alone apks that you can add to any ROM.