If you change your mind, most adult cats won't hurt a kitten. Bowl them over, yes, and the kitten probably deserved it. Actually hurt them, no. (Kinda like humans - most humans won't hurt a kid.) That said, the cat may not actually accept the kitten, but you'll have some time to figure that out.
The biting is also part of cat play, though definitely on the rougher end. Often, the cat learns not to bite from other cats (adult cats don't generally like it when the kitten is biting at them, and the kitten flattening paw is a handy teaching tool). You can teach your cat not to bite, it takes patience and consistency, followed by positive reinforcement when they don't bite.
Example situation:
My cat bites at me. I immediately pull back and say "No", in a firm tone - not angry, just be clear that it was bad.
Next time, cat doesn't bite, I continue to pet/play/whatever, and cat figures out that not biting is better.
This won't be fast, it will take some time to get the message across and properly reinforced. A generally friendly cat will figure it out though.
Also, I don't punish them if they're defending themselves or for accidents. I do try to prevent situations where they'll feel the need to defend themselves, and if you're playing with your hand and you accidentally get bitten that's kinda your fault.