The ship is very modern, i cant say much about the independance but i have sailed on the freedom, which is a sister ship, i would advise the travel agent when you book. The public areas are very spacious and the lifts again massive, the soda package is aprox $85 dollars!
I have tried to check the price of the soda pakage for you but the RCI site is having problems at the moment - the price is, I am sure, $6 or 7 per person per day (you don't have to buy it for everyone if you don't want to) so cost depends on the length of your cruise (not $85 as stated below). If you go on to royalcaribbean.com you will find loads of information. There is a section on accessibilty for disabled passengers and if you use the drop down boxes at top of screen you will find answers to all (or nearly all) of your questions. The FAQ (frequently asked questions) section is also very helpful. Have fun searching around the site.