QIf there are 2 copies of this follower in my cemetery, and I play a Dragoncraft spell during my turn, can I pay 1 play point each to put them both onto my field?

AYes, you can.

QIf I destroy a Star Phoenix on my field with Conflagration, can I pay 1 play point to put it back onto my field?

ANo. When you play Conflagration, the Star Phoenix isn't in your cemetery, so its ability doesn't trigger.

QIs this follower's automatic ability only valid when this follower is in my cemetery?

AYes. If this follower is in your cemetery when you play a Dragoncraft spell during your turn, you may pay 1 play point to put this follower from your cemetery onto your field.