Elbow pain could be caused by locking your elbows as you ride. It could also be that you're supporting your weight on your arms. Your body should be balanced on the bike so your arms almost hang off the bars. Check your position and relax. If you still feel like you're doing a slight pushup as you ride, recheck your fit. I had similar elbow pain and I wound up getting wider bars, a shorter stem, and lowering the bars.
As for needing food after an hour... most people don't. Eat if you feel like it, but after a month or two of solid riding, your body should adapt.