I don't know that it's normal, but it's not unheard of, obviously. A friend of mine has a super anxious kitty who has been completely transformed by Prozac. I never used to see her out when I visited, but now she's always around, even if she is still a little hissy.
No, you don't just randomly get Bengal cats without knowing! Even half-Bengal. Your cat is a lovely tabby domestic shorthair. 95% of cats in the US have no breed pedigree.
Domestic long hair (or short hair -- is your cat young? might be kitten fluff). 95% of cats are no specific breed; it's not the same as dogs.
Very adorable!
Milk production can start two weeks before delivery, so your cat isn't necessarily overdue if you're just basing it on that. Have the babies "dropped" (position shifts down shortly before birth)? When did she mate?
I have Pretty Litter in one box and regular clumping clay in another box. My two cats seem to prefer the Pretty Litter (or maybe just the box -- it's a different shape than the other one), but I like to give them options while still having an easier way to monitor their urine pH and more easily...
There is no reason for her to have kittens. There are too many stray kittens in the world to begin with, and pregnancy always puts the life of the mother at some risk, not to mention (again) the risks for cancer and pyometra. You should spay your cat.