as far as the save thing goes I am programed by from soft but I think it's nice to not be put in a position where you have to do a major enemy or a tutorial twice. I don't think you need to save any other data at that point but the significant unlocks. (I believe metroid works this way as well).
The spell crack sounds like it will help a lot. Unless there is somehow a way to make it not a hold and do a combo thing but instead just hold and cast or just do a combo (if that is articulated in a way that makes any sense) but I assume that would go against your vision for the spell mechanic.