Also, I'm pretty sure you cannot get the DDP on a land/sea package. You must have a park ticket for evertday you are on land (4 days).
Actually for 2008 the basic dining plan
IS available for Land and Sea packages. You have to type "DINE" into the promotion code box on the website, inform your travel agent or the CM booking your cruise that you would like to take advantage of the dining plan while on the land portion of your Land and Sea Cruise. As of right now, the dining plan is only available for bookings for Land and Sea Cruises in 2008. No word yet on if if will be available in 2009 (the CM was not able to add it to my December 2009 Land and Sea Cruise).
Yes your hotel selection is limited depending on your stateroom category and yes you can add an extra night on in advance of your land package but in order so that you do not have to check in a second time at the start of your Land and Sea package, the extra night must be booked through the cruise line.
You will receive a 5 day park hopper ticket on a 4 day land and 3 day sea package and a 4 day park hopper ticket on a 3 day land and 4 day sea package.
As for a passport, this is what the Disney Cruise Line website has to say.
My Passport
Guests are responsible for obtaining proper documentation to board the ship. U.S. Government passport requirements continue to change; therefore, we strongly encourage Guests of all ages to have a valid U.S. passport for all cruises. Having a passport allows you to always be prepared to travel wherever you wish, and offers an added measure of security when you're traveling.
For
air travel, however, the deadline was January 23, 2007. This means that all travelers, including U.S. Citizens and all foreign nationals, traveling to the United States by air, such as Guests flying to Orlando, Florida from Canada, are required to carry a valid passport after the effective date.