I've never heard any difference for duck eggs. Pointed end down, never let them get too warm, or too cold.
You'll find all kinds of theories on storage length, usually saying 10 days or less is best for development.
But I let my broody duck collect her eggs until she decided to stay on them. I never broght them inside. She had a nest of 15 (one per day) before she committed to sitting. I marked the first 7, in case I needed to remove really old ones. Around day 5 or so after she started sitting, I candled them when she was taking her daily food break, and had a few clears, but she hatched 10 of the 15. I'm fairly sure the oldest one hatched.