Sleepover etiquette

We're planning our first sleepover for Andy in a few weeks as we're making plans to have one of Andy's best buds overnight. He's thrilled and I'm a little curious how all this works. It's been a good, oh, 30 years since I had a sleepover and I'm way rusty on the etiquette of all this. Plus, they're boys so that's going to be a bit different than my perspective as well. Other than making sure we wear full-body pajamas in case of any late night visitors not my own and keeping the parents on speed dial just in case, what do I need to plan for? Any special rules for sleepovers for 4 1/2 year olds?