It is possible for a cat to stop having kittens in the middle of having them as its labor period runs for almost 24 hours in durations of two to three hours. The duration is not standard so you will have to prepare yourself with all the necessary requirements.
Both those guys are right by here are other tips! 1. Don't touch a mom in labor 2. Don't touch the kittens for at least a week because they are so weak fr our hands 3. When the kittens are weaned spay the mother it helps preset cancer 4. When the kittens are 10 weeks old you MUST sell them or the mother gets to stressed out and can hurt the kittens, you, or herself! Also kittens can suffer from litter mate syndrome which can cause health issues -VET
Yes, some queens (mom cats) will have breaks between births. It's nature's way of conserving strength. However, if it's a gap of over 4 hours between kittens, you need to call the vet. There may be a serious complication. I think you need a few more tips than we have room to give here. So, here's a great link (from a vet hospital) that gives plain but detailed explanations of the WHOLE process, and what you should expect to happen (so you won't be shocked, like when she eats the placenta), and what you should and shouldn't do. Please read it -- it isn't that long, and you'll be able to help her MUCH better when you know what to do and what not to do. :D http://www.cat-world.com.au/parturition-birth-in-cats