There is no cart from the ship to the cabanas or the cabana check in. We get a cabana when traveling with our elderly, mobility challenged parents. The concierge host in charge of the cabanas called before
Castaway Cay day to see if there was anything he could help with for the cabanas. I asked if it were possible to have my parents transported by cart (we would walk/take the tram). You would've thought I asked him to gold plate the entire ship. With two wheelchairs, the walk to the tram, the wait to get on the tram (had to wait for 4 trams since the crowd was large so no room for the wheelchairs beside the handicapped row which were in use by others in line before us) and the wait for a golf cart to then take us to the cabana, it was 75 minutes from leaving the ship to arriving at the cabana. If I hear that others have received this service, I'm going to be REALLY mad!
If you want to be close to food/bathroom/Pelican Plunge go with the lower numbers. We are usually in 2 or 3 so it isn't a long trip to Cookie Too or the restrooms but the trade off is that it is closer to the line where the Public area and concierge only area of the beach meet so we have had a number of people move into the "less crowded" concierge area.