Could you please help me correct these sentences I'm having trouble with?

- How does your hair look naturally? Is it straight or curly?
- Are you the same when you are alone as when you're with your friends or are you different?
- How low/deep is the subway? I had to walk down 6 flights of stairs.
- They people tend to hang out with their own. They don't mingle with others from different cultures.
- If I had to work 14 hours a day my body wouldn't take it/hold out.
- Why do I feel more tired and irritable on/after two to 3 hours of sleep than 10 hours?

Thank you

the people

than after 10 hours
Anyone please give there opinion on these questions?

 Philip's reply was promoted to an answer.