1. It depends on your state.
2. For example, New York's laws state that if you are sexually active -or- if you are over the age of 18, you need a pap smear before you are allowed to get birth control. Planned parenthood requires it, as do many private clinics.
3. it's not scary! It's not that painful either. If you use tampons, it's only a little bigger than that. Most gyns are very very kind; they know what you're going through! It doesn't take long. He or she will smoosh your stomach a little (always tickles and makes me have to pee!) to check on your uterus and ovaries. Then they'll lube up a speculum and insert it, widening it once it's inside. Then, they'll stick in a giant q-tip to swab your cervix, and you're done!