Bonjour,

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 "not really correct enough" to use in a printed book (a novel, etc.)  I'm pretty sure I've seen i in - say - popular novels from "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 generally 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.

8. Just for the record it is used somewhat technically by mathematicians, computer scientists, when discussing ongoing series, etc.

I hope this helps give the feel!

Cordialment,