Look at Shoretrips.com
for some tour options. Those ports are perfectly fine for booking your own tours. Just know that if you book private tours the ship doesn't know where you are, while they do know who is on the ship's excursions. Not that it is likely, but if a ship's tour is late getting back the ship will wait. If you are late returning from a private tour you could find the ship has sailed without you. But this is quite rare since the private operators know the schedules too.
You cannot bring personal alcohol aboard. Strictly speaking, the RCI Beverage Policy
doesn't allow any personal beverages. However they usually don't say anything if a guest brings a reasonable amount of soda or water. (Like a 12 pack).
You can find iced tea in the dining room and buffet restaurants at meal times, and from room service. Just know this: iced tea on cruise ships is not that good. It is usually made from a concentrate. Possible option: you can get hot water and tea bags 24/7 at the Cafe Promenade. Bring an empty thermos jug with you and make your own tea. Then all you need is to get a glass of ice at a bar and you are set.