5) Just like that. PWR for a forceful attack on a single target. DEX for a fast wide area attack. Alot of electrical magical is that way now. Makes sense to me. Other elements will be getting a similar treatment (maybe with different stats) from what I heard
6) A White Mage can learn an ability to use shields, that mage can then multiclass into a different class and keep that ability.
8) GMs can hand it more often if they want. One GM I know about hands it out like candy, enticing people to use it more often rather then stockpiling it.