Booking hotel (date and guest)

I have 2 questions, can anyone helps me get the answer

1. When you booking hotel:choose range date, from check-in date to check-out date OR choose check-in date then choose how many nights stay. Which is UX more and why?

2. When you booking hotel, hotel require you enter number of rooms, adults and children. Can we dont require user enter children? it means just enter rooms and guests?