Registrants from my onZoom event didn’t receive notifications, why?

I have 4 questions, I hope someone can give me some answers. Thanks in advance! 

1. The registrants from my onZoom event didn’t receive notifications, why is that the case?
2. How come my registrants that got a free ticket did not receive an email notification?
3. How can you do a poll with an onZoom event?
4. Why is onZoom not available to non-US?