I would suggest getting them duckling food unless there is plenty of food for them to forage for, as giving them adult food could poison them with too many minerals or stunt their growth without enough protein. You could feed starter for just the first week or so, and then let the ducklings out...
I'm not quite sure what to think. Pekins are a large breed, so maybe she is accidentally breaking them when she gets up to feed. Perhaps another hen is breaking them.
Sounds exciting!
Are the eggs being eaten or are they just infertile?
As for the duckling, mother hens almost always know just what to do. If the chick is being kept warm and isn't giving out frightened cheeps than it should be happy. They have a yolk that they absorbed before hatching and...