So, like, these vampires can go out in daylight?
Yes they can - but bright sunshine makes them glitter like quartz, making it quite obvious that they're not human. Cloudy days are fine for them though - hence the Cullens' decision to live in rainy Forks, Washington, rather than, say, Florida.

But they still drink blood, right?
Yes they do. The Cullens, however, drink only animal blood, and as a result have amber-coloured rather than red eyes. It's a sort of vampire vegetarianism. You can tell a hungry vampire by the fact that their eyes get darker and darker - so if they're black, get your skates on and get out of Dodge.

So why are they all so pretty? Is this a Hollywood thing?
No, it's in the book. Several of the clan were already good looking as humans, but turning into a vampire makes you better looking. Edward and Carlisle theorise that this is to make vampires more attractive to their prey. They also smell good to humans - and vice versa.