Yes. It doesn't take that long. If the young man ejaculates while the two are having sex, the girl can become pregnant is she is or the boy are not using protection. You dribble become you shoot often times and it does not take a full blown ejaculation for her to conceive
Yes, it is possible. Pre-ejaculate can contain sperm, and it can cause pregnancy even if ejaculation doesn't occur. It is less likely, but not impossible.