Search the forum and find out. 
If we do find a duplicate this can be merged into that topic, adding the votes to the other topic.
Impossible to say. As I said, this is one of many factors Asana take into consideration.
There are feedback threads with >1k votes that haven’t been implemented, and there are threads with one vote that have been.
The challenge for Asana is finding a balance between listening to feedback and steering their own course.
Here is some reading material that I think are helpful in better understanding Asana’s perspective on feedback: