We did WDW before and after a cruise last December.
Getting to WDW from Airport: Magical Express...the usual.
Getting from Resort to Port: The night before they will provide instructions for your luggage and your pickup. For us, it meant that Bell Services at the resort came by at 8am, and picked up our luggage. Further, we were told that we'd be picked up at 11:30am, so we spent a couple of hours at Epcot (we stayed at Beach Club). At 11:15 or so, we made our way to the rendezvous point which was just a lounge area at Beach Club. There were maybe half a dozen other families there. A
Disney Cruise representative was there confirming that our luggage was picked up, and then walked everyone over to the Disney Cruise bus. After riding the bus for an hour, we got off at the port. At that point we only had our carry on bags (a diaper bag and backpack), and we were told that our luggage would be placed outside our stateroom that afternoon. Went through security, and boarded the boat to begin our cruise. The luggage showed up around 430 if I remember correctly.
Getting from the Boat back to WDW: The night before getting of the boat, we were given a time that we were to report to a Disney Cruise bus to take us back to WDW. I think it was 830. We were also instructed to have our bags outside of our stateroom by around 8pm the night before. We woke up, had breakfast, then got off the ship, then went to find our bags. Once we grabbed our luggage, we went through customs which was very quick and easy. Then we walked the very short distance to the Disney Cruise buses. The bus dropped us off at our resort (Grand Floridian this time) where we dropped off our bags with bell services so we could go back to the parks. When we returned to the hotel that evening, the room was ready, and we called bell services from the room phone, and they brought up our bags.