Do you have to be a guest at the hotel to utilize the rooftop bar?

You don't need to be a guest at the hotel since my friend made a reservation without being a guest. The caveat is that the elevator won't take you up to the top floor unless you have a room key to allow access. If you have a reservation but don't have a room key, you simply alert the staff at the front desk and they'll escort you to the elevator and allow you access to the top floor. You also don't need a reservation but I strongly encourage making one. I was staying there last week and had a dinner reservation so we could watch the Disneyland fireworks show (fantastic place from which to watch the fireworks). Several small groups showed up without reservations. Some were seated. Some were turned away.

You need reservations, don't know if the current residents can just get in. Its nice because it keeps all if the riff raff out.