Customs/immigration came onboard our ship and they were located in the World Stage. Even if you were self-assist, they did not allow any luggage at all in the World Stage area, even small bags were not allowed (those were customs/immigration rules). You were to leave it everything in your cabin, and once you completed immigration/customs, you go back to your cabin, collect your luggage. Then proceed to the gangway where they scan your card, check you have the little sticker signifying you completed customs/immigration, and away you go. I never heard of, or saw any "line" at the actual debarkation gangway area.
BTW... the amount of time with a customs officer was also less than 5 seconds, kinda funny really.
Lot's taxi's out front, not sure about Uber.