J.B.
I've been running 2-3 miles 3-4 times a week for a while. Running every day is not a good idea unless you're in great shape. You can injure yourself by running daily - on non-running days, try walking, biking, swimming, strength training or something like Yoga or Pilates to make sure you're working on strength, flexibility, and upper body.
I don't eat differently on days that I run, but again, I'm not out for hours covering mile after mile.