Why do you need gender?
Gender is used for reports. It can also be used to fetch a particular subset of users in order to be targeted with content, ads, etc.
Why do you need country of residence?
Country is used for reports, especially for international clients/customers. It can also be used to fetch a particular subset of users in order to be targeted with content, ads, etc.
Why do you need birth date?
The birth date is used to determine age and is used for reports. It can also be used to fetch a particular subset of users in order to be targeted with content, ads, etc.