Quick question on Muscovy ducks and laying

[Irukanji]

So anyway, within the last few days(yesterday, I believe), one/a few ducks laid 3 eggs, and another one today. They were temporarily handled(carefully, with gloves, and only the first 3 before the 4th was laid) to put some hay under them(they were laid directly on the blue gravel, so this was the smart choice). So we have 4 eggs. The mother was sitting on them when I looked earlier today(about 8am....freezing cold), but she isn't currently sitting on them during the day(to the best of my knowledge). Is this normal? When/should I start seeing her on them more and more? I'm also expecting another 20-odd eggs assuming the 20-30 egg average for muscovy's, and they have plenty of food(and more than enough water).

And when they hatch, should they be kept inside and warm or should they be allowed to do what nature intended? We are hoping to breed them for meat and/or to sell. An incubator is out of the question currently, until my parents make up their mind as to what they want to do in the long run.

Thanks.

EDIT: Someone didn't count them properly, and there are actually 5 eggs now. 1 was hidden beneath some straw, as can be seen here;

The top left egg doesn't look like the rest, much smaller and different coloured(???) It could just be the flash.

 

[satay]

just leave them be the mother will sit on them after she is finished laying if she decides to go broody. If it is warm (outside temps)when they hatch you can just leave them with the mother unless you have a drake in there too. I tend to take the drakes out as they have been known to kill babies at times.

 

[Irukanji]

The big brown drake will come up to check on the hen in the morning, and sort of just cruises around before going back to the lake. Outside temperatures at night are sitting around the 2-4C mark, daytime temps well below 15C, average has been 10C. The ducks are free to roam, they have an island in the dam they can sleep on, but this hen has decided to make itself a nest in the shed(of all places). It is well sheltered, the dogs wont see it, but a fox might smell/investigate in there which is my only concern(the only way in for the duck is a narrow passage behind some boxes, even from the entrance to the shed I can't see the hen sitting on the eggs directly).

I guess I'll just wait and see.