Today's burning book-filing questions

I'm not looking for the official library answers; I'm curious what others think. 

1. Do you mix hardbacks and paperbacks?

I do not.  I recognize the down side of this choice: To find all of an author's books, you have to check in two locations.  The up side, though, is more important to me: Mixing mass-market paperbacks with hardbacks tends to cause warping in the hardbacks, particularly on very full shelves.

2. How do you file the books an author writes under pseudonyms?

This one is trickier, because there are so many good answers.  I tend to put all of an author's hardbacks together, even if she/he wrote them under multiple names.  So, my Donald Westlake and Richard Stark hardbacks stand together.  Even with this choice, though, I am torn on whether to put Stark after Westlake, mixed with Westlake in chronological order of publication, or before Westlake. 

These are the sorts of questions that a person who lives in a library spends entirely too much time discussing and pondering.