Both your problems can be solved by either using more white magic to heal (I rarely touch items unless it's urgent or yuna's out of mp) and battling more. battles=experience+gil. sounds like you need both.

also, dont' bother healing if you're going to be near a save sphere. that's a good way to level up, just find a save sphere nearby, and fight monsters 'til you're almost dead, then go and heal^_^