Breaking at 80 characters is something you do while coding, not afterwards. Same with comments, of course. Most editors can assist you in seeing where the 80-characters limit is.
(This may be a little OT, but in Eclipse there is an option which formats the code when you save it (according to whatever rules you want). This is a little freaky at first, but after a while you start to accept that the formatting is no more in your hands than the generated code is.)
