OK here is the scoop.....
Excursions:
We didn't do anything on Key West, Grand Cayman was the best...we did the turtle farm & stingray city, I HIGHLY recommend stingray city...definatley a must. On cozumel we did snorkeling but that was not good, the chacunnab (sp.?) national park smelled like a toilet and was not very fun not to mention there was not coral or many fish. The tour guides begged for tips all the time and were mad when we didn't pay. I recommend the swimming with the dolphins excusion instead.
Castaway Cay we went parasailing and that was really fun I recommend that also. Well worth the money.
Soda:
I had read before I left that the soda was going to be flat...but to my surprise it was great. Yes you do have to pay for soda at the bars. You get it free at the meals and at the stand on deck 9. It was only flat like once and for about an hour. Disney has really cleaned up that problem.
Dress:
The personal Navigator will tell you how to dress for dinner but on the casual nights we just wore whatever we had on and that worked out great. On formal nights the men and boys wore things like kakhis and a button-down shirt or polo shirt. Some children had ties that looked nice. My brother (11) and I (16) wore kakhis and button shirts that worked out nicely...hope that will help.
Soda Mug:
Yes, there are soda mugs avalibale for purchase onboard the ship. You could get them at most of bars and at mickey's mates.
FYI:
I recommend booking excusions *before* you leave because things fill up very fast!!!
And remember to get reservations for Palo right when you get onboard.
HOPE THAT WILL HELP!!!!
ANY MORE QUESTIONS???