@aahz: The ages we know for certain are:
Dick was 21 at the start of the New 52 when he went back to being Nightwing.
Babs was 21 at the start of the New 52 as well.
Huntress/Helena Wayne was also 21 at the start of the reboot. As she was 16 when she came to the main Earth, which was 5 years ago. She is the same age as Powergirl.
I would guess that Luke Fox is also probably 21. That seems to be the age they like to stick everyone at.