Would you like to see another user's gender and age in his or her profile screen?
It has an equalizing affect in discussion if that is now initially known.
Yes, but optional.
I don't see why it would really matter. As EarlyBird said, let it be optional for a user to display this information.
Although I do sometimes wonder some people's age, many people will not debate when they find out they are arguing with a teenager. Just because they're young doesn't always mean they're stupid.
Those who want us to know such things, let us know. There are many here that keep their sex and age hidden for a reason.
I believe that if people want such to be known - they express it in their interactions. Personally, I already have my gender on my profile - but a lot of people know my age anyway. If people want it to be known, they'll let you know in comments, etc.
Yes, but not required to have other things public.