Technically, if it's at the end of a sentence, it's supposed to have four dots (three for the elipisis and one is a period.) Unfortunately, that doesn't pass MS word's muster.
Starting a sentence with a conjunction is a gramatical error; however, that doesn't stop people from doing it. Language itself is like sand, as X.J. Kennedy put it. It is ever shifting, and changes to suit the zeitgeist. If you do not believe me, read some medieval tale in the original middle English. Most of the words in use today were, at one time or another, slang.