Yeah, makes sense.
That's possible. Are there other roosters around? Do any chicks have feathered legs (even just a little), beards/muffs or any other dominant trait that would indicate a different parentage?
Or, could the eggs have come from a different hen?
I've got hens like that too. Eggs can last up to 2-3 weeks, give or take, but after 1 week the chance that they'll hatch goes down. Still, they could hatch.
Sounds good. There is a chance they won't hatch or be fertile, and if she doesn't go broody soon you won't get chicks. Can you find fertile eggs to add to her nest? So there are more and she is more likely to go broody.
There's a good chance the eggs are fertile. I'd let her try to hatch them (if that's what you want). I would set up a safer nest, move her at night and lock her in it for the first day or two letting her out to get food/water/poop.