Duck egg requirements?

[Bettacreek]

I posted this in the waterfowl section and still haven't had any responses. Yes, I know, I'm being impatient, but, the eggs are now here and I really need to know what requirements are on call duck eggs. There are ten, two have hairline cracks. I can't even tell which end is supposed to be up... I can't really see an aircell in them, and both ends are shaped the same way. She said that duck eggs are 28 days, but what humidity do I need to put them in? I assume that the temps are the same as for chook and quail eggs.