Carnival used to enforce the policy that diners would not be seated more than 15 minutes past the set time. On two nights during our recent 5 day cruise, a couple was seated a full 30 minutes late and our servers had to scramble to serve them.
Yes to all. You can also use it to chat with anyone on the ship who has activated the chat app {$5 for whole cruise). You will make your dining reservations with it and schedule your debarkation time. You can review your S & S account in real time as well as your casino account.
We go to our muster station as soon as we board. We never waited in line since the new program was instituted. If several people get there at once, they do the demonstration for the group, scan your cards, and you are free to go.