Can you play and finish DA: I without healing spells? You must because there are is no healing in the game. Take it as a new system where such skills are nonexistent. But have no worries because as Lukas from BioWare writes here you should be fine.
But what about Easy? Well, last weekend, on Easy/Casual, starting the game with a mage and me not saying a word, my seven year old played for two hours that included many battles, including rifts and beating the crap out of a low level Pride demon. No party wipes. I covered his ears once.
Many, many more concerns are answered here by BioWare.