You can clip that. Do you have any neosporin without pain reliever? That's generally safe to use. And corn starch will stop any bleeding.
When do you candle the chicken eggs and when to toss bad ones? - Page 6
You can leave the one that's already hatched in the incubator. It's cheeping and movements will help motivate the other chicks to hatch. Just be patient and wait. If you notice it trying to make pecking movements, but aren't seeing any progress towards zipping, it might be time to very carefully and gently assist. I do suggest you read this article before you do anything, though.
Oh and thank you about the feet you were right, they fixed themselves