1. BTW in that example I'd say you would **not** have the last comma.  So it's: Things like a, b, c, d...

2. Certainly in English people use that form in emails, for sure.

3. It is completely normal and understandable to use an ellipses for unfinished, continuing, lists.

4. **Note that one particular use is to strike a humourous note**:  And here is my ex-wife Cindy.  And there are my ex-wives Helena, Georgia, Audrey...

5. You are quite right that it is a little "not-correct enough" to use in say a printed book (a novel, etc.)  I'm pretty sure I've seen it more than once in - say - popular novels like "Tom Clancy" or the like.  But you're right, it's "not very posh" so you, generally, wouldn't see it in literature.  And it's a bit too jokey for non-fiction.

6. I'd say you'd see it in magazines, certainly anything like Playboy or Wired or the like. It would certainly be use (particularly for sarcastic, comic effect) in magazine articles in the UK by - say - Jeremy Clarkson.

7. It is completely and absolutely 100% understandable as an "unfinished list" to any anglophone.

I hope this helps give the feel!