if you have sex that doesn't mean that you are going to get pregnant right away. If you are prepared and have protected sex and are safe then you won't get pregnant and if you use a condom(a really...
While certainly possible, not every unprotected sexual encounter will result in having a baby. The most fertile days of a female are an individual thing and have to be carefully tracked. Even then...
Traditionally, yes. There are a few other methods such as artificial insemination, but one way or another, the sperm has to meet with the egg and implant.