Yes, after completion the new quest is generated instantaneously but you still have to wait 12 hrs for it to be able to take it. Maybe the news need a different choice of words to make this clearer.
Oh yea, definitely. Also because, actually, it's non a matter of "generation", but I think (correct me if I mistake) that the NPG proposes two quest at beginning and after the player chooses one, the other one becomes eligible only 24 (12 if premium is activated) hours after the first quest is completed.
Anyway the prob is that NEWS have to be revised periodically by some moderator anabled to do that, or let the players to post replies on them...