I want to know whether there is a way of getting information such as age, sex, country of origin, etc. about the users of Super User. It would be a great tool to know what type of people are affected the most by Super User.
You can compose an SQL query that will search the most recent data dumps. Profile information you can get is:
So from your list:
age, sex, country of origin,
Gender is not an option on profiles, and we can't force users to give to us - but there is some information available.