Middle of the day? 530-830 people are wanting to get home, make dinner and settle down. These are the slow times. After 830 it picks back up for people who are studying or chilling on their laptops.
I agree that another hour of staff time would be best, but they must be doing a major overhall.
As to why it is Tuesday, I am sure they have marketing information that that is the least utilized time of the week.
How much money do you think it would cost starbucks to close down for an apple announcement. Thats crazy.
Also, as a large company I would imagine that their systems would have an iPhone plugin and would just receive the orders then yell out the name. There shouldnt be much of a change, it will mess up business operations if it does.