This downtime has nothing to do with light bulbs being replaced. Lighting equipment is maintained daily.
Nope. A show doesn't go dark for one day due to cast vacations, nor does it happen for training purposes. Cast vacations happen when they happen and training takes place twice a year in conjunction with the regular show schedule.
Again. Nope. The dragon doesn't get rebuilt "this time of year". It is maintained daily, just like everything else in the show.
Maybe.
Aren't you just a magical breath of fresh air?