Are you talking about the trio of rats (I'm assuming you mean the furry kind) laid a clutch? They don't lay eggs, they have litters.
If the male rat is sneezing alot with red discharge around the eyes/nose it is probably a myco flare up. Or because he is stressed. Aspen shavings are fine for rats.
He doesn't sound congested (from what you say, it is just the sneezes) so you can move the humidifier. (if it sounds like he is making "monkey" like noises then the humidifier might be a good idea)
If you are breeding in a "ferret mansion" then you might want to put some 1/2 inch wire mesh around it, for the babies will be able to walk right out.
Try putting something for them to snuggle on (yes, I own pet rats, how can you tell? lol) 72 is a fine temperature (if you are breeding I had better luck with cooler temps, more around 68-70 degrees)
you won't be able to buy breeder rats from a breeder (breeder in your case meaning for reptile food) as most real rat breeders are against it

because "most" (I'm not saying everyone, as most people here humanely kill the rats they feed) are against live feeding and inhumanely killing them.
So your best bet would be to find a reptile food breeder and buy some adults off of them, or go to a pet store.
BTW why would you be breeding wild rats? As far as I know most rats in pet stores etc....are "cb"