1. I'd say wait it out and see if time adjusts the problem. If the person is not normally an ego person they may just be having a problem accepting their new role. If they have had issues with their ego in the past, they may need a humbling experience to balance it out.
Personally, I've always found promtions a humbling experience because I associate promotions with having to hold myself to a higher standard and not wanting to fail.
2. If this was the first time the teacher ever hit intentionaly, then they may have just been acting out due to anger, frustration or other emotions. How well do you know the person? Is this normal for them? A one time deal, out of frustration, I'd let that go.
If this is the way the person is, and you still elect to train with them, then accept the hitting as part of your training or knock them on their asp and go from there.
Now, accidents do happen. I was helping one of the students a few weeks ago with sparring techniques and punched them in the eye. It wouldn't have been a problem, but I didn't have any hand pads on, so the eye closed immediately.
I believe the student knew the hit was not intentional, but if they think too much into it, they may wonder if it was a lesson?
Do some teachers treat students like that? Yes, they do. I know one teacher in particular. He treats all his students that way. I watched him slap one student across the face for not paying attention while he was talking to the class. He routinely blasts them.
I have little respect for this person because of their actions. On the other hand, the students that stay with him can take anything and are very good at their art. It's a double edge sword.