maybe they do, rodentpro sells them
Yes but rodent pro sells food for many types of reptiles not just cornsnakes. It is OK to vary their diet a bit once you know they are good eaters. I certainly wouldn't try offering other types of food if it is possible she is gravid. For a time before she lays eggs your snake may not eat. I guess I wouldn't chance a different diet right now if it were me.
No Cypress either stick to aspen, sphagnum moss, carefresh bedding, newspaper, the cotton you're using. One thing about aspen or carefresh when they poo, you just have to scoop up that spot, makes it easy to clean.
You can get fertile quail eggs quite cheaply on Ebay and incubate your own. They start laying at about 7 weeks.
Good Idea if you're going to fed them the chicks, but the book I read (Corn Snakes and other Rat Snakes ~ Bartlett & Bartlett) said to feed them the unfertilized eggs. Said you could find them in some specialty markets, and from hatcherys. They said that way you'd be sure to get the unfertilized one
I'm not sure about the eggs, but it seems I read one of the experts on here say corns aren't made to be able to digest the shell or something. I do know there are a few people on her who feed cooked chicken and quail chicks. I guess I would worry they would like it more then mice and then you would be stuck feeding chicks.
Corn snakes can be pain-in-the-butt eater: like only wanting live (which is a problem when they are eating full grown mice), only eating fuzzies when they are adults. I have one that will eat rats, one that won't. Sometimes when they are really young they have to be coddled with lizard scent or live pinkies, but once on f/t it is easier.