I have been on Carnival 4 times since being on 02 24 hours a day.
You will have to transport all equipment onto the boat yourself but you can ask for a porter as long as you ride or walk along with the equipment to supervise it.'
The 25 foot cord will be plenty.
Sometimes I drive to the port with my own equipment and sometimes I rent it and pick it up the day before the cruise. I use a concentrator at night and liquid in portables when out of the cabin.