Is she from Outback Reptiles?
They sell wild caught gravid females.
If she is from them, they treat their wild imports for parasites. Not disease though.
You would have to keep her in quarantine away from your personal snakes.
Huge bin?
You will know she is going to lay when she she seeks the hot side and stays in a perfect coil.
Take a look at this reference: http://www.ballpython.ca/gallery/breeding.html
When she lays, she will most likely survive. But if she becomes egg bound (egg gets stuck), she may need medical attention. If that happens, there is a chance she will die. But thats not very common.
Will she eat rats? Maybe, maybe not. That's difficult to say, but I suggest offering her a live small rat once she's settled. It can be difficult to get wild caught snakes to eat.
You don't necessarily need an incubator, but for the best chances of hatchling survival, its best to build one. You can build a very cheap and reliable one out of a drink cooler. Just make sure to get a reliable thermostat.
Here's a DIY reference:
http://ball-pythons.net/forums/showt...oler-incubator
http://ball-pythons.net/forums/showt...bator-Tutorial
She can do maternal incubation, but that means you have to make sure her enclosure is the perfect environment. It is more difficult to control compared to an incubator.
Plus you want the mother to get feeding as soon as possible. She may not eat as much or at all when incubating herself. It can take a lot out of a female.
Maternal Incubation instructions:
http://ball-pythons.net/forums/showt...nal-Incubation