An ellipsis is properly used only to indicate that text has been omitted.
There are people writing these days who seem to know no other form of punctuation besides the ellipses, and, although they don't seem committed to always using exatly three dots, do seem dedicate to using in place of all other marks except the apostrophe and the question mark.
If you are writing dialogue, you can use it to indicate a trailing away of the voice, as though the speaker started to say something, but then changed his mind.
So your first sentence uses the ... incorrectly.
Your second sentence makes what I consider an appropriate use of the dash.
Your third sentence should simply not use the elllipsis there at all. Put a period.
Your fourth sentence should use a period where you have a dash.
Many people consider the dash to be rather an informal punctuation mark as well. I actually use them regularly in my business writing -- but regularly is not the same as excessively.