Ellipses

The ellipsis, unlike the dash, should almost always have spaces on either side (and also in between periods if you aren't using a special ellipsis glyph—this . . . vs. this …).  The exception is with parentheses, dashes, and quotes.  Also, when quoting something that already has ellipses in it, you should enclose your ellipses in hard brackets like so: […].

If you leave out the end of a sentence, odd as it looks, you are to put your period a space away from the ellipsis … .  Here's how you start a sentence with an ellipsis.  … And here's the part you didn't leave out.

My own personal taste is that in both of those cases, you may as well put the ellipses in hard brackets, just so it looks more like a single entity, and not just four periods.

Slainte!