How does the "Taken Over" event card impact buildings and zombie movement?
The building remains taken over even if it has no zombies in it. The Last Night On Earth wiki covers the similar situation of drawing the My God, They've Taken the... card when all your zombies are already on the board:


  with ‘My God, They've Taken the...’ the building is always Taken Over even if no new Zombies are placed.


I think the zombies you place stay put for a turn even if there's a hero in an adjacent space, the Zombie Hunger effect doesn't override the no movement rule.