What kinds of foods do you eat before running? I've found a protein shake and some Chia sesame snacks from Sunflower work pretty well. Zone Perfect bars are pretty good too. Clif bars seem great. I try not to fill up on heavy dinner stuff beforehand because I don't want it to weigh me down.
How much water do you typically drink beforehand? I think as long as you're hydrated, you're good, you just don't want to drink so much it's sloshing around inside you and making you woozy. I've found I can do 7 miles without replenishment of any sort, but I'm sure that changes if the terrain is steeper and the temperature is warmer.
If you do need to eat or drink during the run, do you find it's better to slow down and walk while eating/drinking, or do you just plow on through? I always have a hard time calling it a run if I walk or stop for anything but a shoe tie. And speaking of, what do those crazy ultrarunners do in the mountains? Do they always run the entire way up the hill? Or do they walk part way? I've heard that there's some mantra that it's better to finish slow than to not finish at all, implying they may slow down on the hills. I'd welcome that, but I'm afraid I wouldn't want to start running again after I got to the top.