1) As often as I need to.
2) As often as I need to.
3) As often as I need to.
I may drink anywhere from 10 oz to 50 oz on a 30 mile ride depending on the ride, my intensity, and the weather. If it is sunny, there is no shade, high humidity, and it is 95 degrees, I will drink often. If it is 60 degrees, I may not get thirsty or sweat much at all.
It is impossible to say how often or how much one should drink. However....weigh yourself before the ride and after. If you lost weight, you didn't drink enough. If you maintained or gained weight you drank enough. Every 16 oz of water = 1lb on the scale.
Eating on the other hand. You need to eat about 100 to 200 calories every hour for rides longer than 2 hours.
As for rest breaks. I rest as often as I feel like. On the MS150(78 miles per day, flat course, comfortable temps), I stopped every 15-20 miles. I could have rested less than that, but I was taking it easy.