Duck Expect Again! Why wont my duck sit on her eggs?

It is day 5 of her laying..I have 5 beautiful perfect shaped eggs..But she has no interest in them at all! Every morning I go out to the cage and her nest is always tore up and there are eggs everywhere..You know one here in the corner one over there not in a bunch! She has not stepped on them none are broke..Is there anything I can do to help or make her understand what she is too do! I believe the eggs are fertile she has a male..Why isn't she interested in her eggs? What is she saying by tearing up the nest and laying eggs all over the cage? Does she know or can tell if they aren't fertile? Maybe that's why she wont sit on them? I have decided to buy an incubator wont be here until Friday..How long can the eggs last? Should I do something special to them so I can hatch them when it arrives?How long will they keep goo so they can be hatched? How do you candle an egg? Can I do it now to see if they are fertile or do you have to incubate them for awhile too see???