For any hilly 2.5+ hour ride, I prefer to eat a light breakfast with protein and some fruit. I did a semi-hilly 52 mile traininging ride this morning, and had 1 cup of non-fat cottage cheese, and 2.5 cups of fresh watermelon (water, fiber, fructose/glucose, potasium and trace minerals...).
All that I usually drink during my rides is water, unless it is over 100 degrees F. and I'm craving salts and electrlites, and then I stop at a gas station and pick up a fast sports drink. I prefer gu-gels and real food for my calories. Unless I've been riding for over 3 hours, my stomach sours if I eat more than about 150-200 calories per hour, though.
If I'm riding over 3 hours, I find that it is best to just eat some semi-bland and not too sugary real food sometime around the half-way point, usually when I stop to stretch and/or use the restroom. For food, I like fig bars, fresh or dried fruit, some of the more whole-grain-based nutrition bars (Cliff/Luna/Odwalla), etc. If it is really hot outside, salty snacks like potato chips and roasted and salted nuts also hit the spot.
Keep it simple, make sure to drink enough, and don't eat too much. You should be fine.