Number of eggs at one time depends on the kind if chickens. I have had them lay 4-5 a night. Usual is 1-2 but some breeds lay more than others.

I don't think chickens mind people handling eggs. Have known some people who have placed another chickens eggs under another hen who hatched them all. Sometimes it can depend on the hen's personality. Yep they do have individual personalities.

I would keep an eye on whether the chicken is actually brooding on the eggs ir whether she just layed them & left them. Would observe at this point. Eggs will not hatch if they are in fact fertile if the hen allows them to get cold. That is why people use heat lamps to hatch eggs instead of using the hen herself many times.