Non smoker would be a plus, though not obligatory. You can take your animal if you want as long as you pay attention that he won't destroy or waste the appartement!!
Thanks for your discretion for my neighbours.
The insonorisation is excellent for instance you can push-up the volume on the television or the stereo with no problem or even shout, however my downstairs neighbours (a couple with little baby) should hear a little bit vibrations as you walk (this was an old house before being converted into an appartement). As I am personnaly very discreat they might knock at the door if you walk across too nervously around midnight ... The best is to put off your shoes in the entrance if you don't mind. This flat should not be recommended for someone who would train for the casting of greese or saterday night fever but as long as you don't jump it should be ok!!