We didn't. You'll have to wait a bit, but it's definitely worth it.
No but likely it'll be a few hours wait no matter what they tell you.
You can but not necessary
No, but expect to wait if you're not going very early. My friends and I went on the 4th of July around 6pm and got upstairs after we had one round of drinks. By that time the place was absolutely packed.
We didn't make reservations, but if you want to sit on lounge chairs I suggest getting there early because it's hard to get then once they're all occupied.
Thanks! Your answer is awaiting moderation.