About breathing, I've read that inhale through nose and exhale through the mouth would be most regular. but on the other side, I've read that if you are doing your training in very high tempo, it would be better to breath through the mouth in both directions, because that way you get more oxygen. Most important thing about breading is actually technique regarding harmony and rhythm of breathing.
Btw, don't forget water during hot days if you are running longer then one hour.