the 4-5 nap is the catnap. i wouldn't let him sleep more than that hour. he's probably grumpy because he's overtired if he's been up for almost 2 hours. also, i notice with my LO she won't eat if she's overtired.
if he gets up at 6:30, i'd shoot for a 6:30 bedtime. so after he gets up at 5 from the catnap, I'd bathe him, feed him, cuddle, and have him drowsy and calm and in bed for 6:30.
melissa