All my mom has ever been worried about is that i drink safely if i'm going to drink. If i'm over at someone's house, she could care less if i don't home come - she prefers i sleep over no matter what.
I also had the situation where parents offered to pick up if i had been drinking, but i never had to use it.
I think you do have to teach kids to drink safely, if they are going to do it. It's really a life lesson. When i turn 21 in a few months, nothing should change. The lessons you learn underage are the same things you follow when you are older.
About the whole sex thing...i don't know if teaching abstinence really works. Kids are having sex in high school these days in high numbers, if people told the truth through high school. They need to know the risks involved as early as possible.