I would say that 70 percent of married couples probably had sex within the first 2-3 dates. You need to be the best lover she has ever had. Manual and oral stimulation is usually the most intense and focused. Intercourse is a more total experience though. You need to find out what she likes.
Casual sex is a normal part of youthful experimentation.
The more partners you have contributes to cervical problems for women, and then there is the chance of getting pregnant. It is very difficult to know when it is true. You would have to look at his behavior over time. To become more adventuresome, you have to take sex a little less seriously. You have to allow yourself to make mistakes.