4A: For puzzles, not problems                        - MATHEMATICS
 5A: Recent puzzle, “Surviving the Zombie ___”        - APOCALYPSE
 7A: Endlessly talked or whined                       - YAMMERED
11A: Endothermic, like birds and mammals              - WARMBLOODED
13A: Definitely out of this world                     - EXTRATERRESTRIAL
14A: Orange, kind of                                  - NA??L
15A: May earn you +2 reputation                       - EDIT
16A: Informally, “Vandy”                              - VANDERBILT UNIVERSITY

 1D: Stack _______                                    - EXCHANGE
 2D: Name of a kind of pi(e)                          - RASPBERRY
 3D: Often run-down, very cheap lodging; a dive       - FLOPHOUSE
 6D: Ta, W, Re, ...                                   - OSMIUM
 8D: Foremost tag on Puzzling                         - RIDDLE
 9D: Ravenous eater; lover of (too much) good food    - GOURMAND
10D: Evidently, how “Slurm 7-packs” should be shipped - EFFICIENTLY
12D: Employer of Linus Torvalds in 2000               - TRANSMETA