Peanut butter and jam sandwiches are good to eat on the road. Easy enough to eat on the bike so I can keep on going without having to pull over and stop. I also like dried mangoes and trail mix type things. If you have a stove instant mashed potatoes are awesome to eat too. I try and stay away from too much greasy food since it tends to bother my stomach on a long hot ride but everyone is different. I like to experiment as I ride; Asian noodle dishes and pasta can also be good sources of food provided they aren't too greasy.
I also try to avoid drinking too much water, the body can only handle so much every hour... I would say my maximum is less than a litre an hour, probably closer to 750ml an hour in hot conditions.