>are you supposed to go up to a customs agent
>yourself or with your group of friends you're travelling with?

In your context by yourself.

Just make sure all your stories match up - If you say you're going to Vegas for a holiday and then your buddy behind you says the two of you are going to Vegas and then on to LA you may get pulled out at secondary - It happned to a friend of mine.

Cheers,
Geoff Glave
Vancouver, Canada