In the User CP section, under edit profile.. there is a spot there (under privacy) where is says display age and full date of birth near the top. If you have that displayed, or just birthday only, it should show up in the calendar.. hope that helps!
I would just email or call up the people that you haven't heard from and remind them of the dec. 1st deadline. If they don't respond by then, it will be their loss.. not alot you can do about it unfortunately. Hopefully if you remind them then people we make the effort to respond.