I just got home last night on the 8/26 sailing, and concur what you said about on boarding. The debarkation process at the end of the cruise was even easier, by far the best of any port I have been on.
I stayed at the Hilton Diagonal Mar prior to the cruise which is one of the cruise sponsored hotels though I booked independently. They offer a shuttle for 30 EUR or a tour to Monserrat for 60 EUR that drops you off at the ship. We elected to do a Taxi - 24 EUR including gratuity.
As far as boarding:
You can purchase wine and alcohol as well as other beverages. Bottled water was 1.5 EUR for a 1.5 L bottle or 8 EUR for 6. Much cheaper then on the ship and we used these in our room. 6 pack of soda, 6 EUR. Again cheaper than bars on ship, so nice if you want them in the room and you don't feel like going up to deck 9 every time you want a soft drink. If you buy alcohol they will take it and store. You can buy your two bottles of wine right there and prices seemed reasonable.
As far as getting off at the end:
The gangway opened for express walk off at 6:30 and there was a huge line, for those trying to get to the airport for US based flights (know there are some to JFK and EWR that left before 11).
You do not go through customs at Barcelona port nor do you have to show passport to leave. Showed KTW card on deck 3, walked down the ramp, picked luggage up in the same room where you wait to board and walked out to the cab line. This was around 7:40 and all luggage was already out. If you have not booked transfers to the airport (
DCL charges $30 pp), cabs are plentiful. Flat rate of 39 EUR to the airport, gave driver a 5 EUR tip and he was very appreciative. Porters are different then they are at Port Canveral. No one is hustling, but there is a company if you are interested called bags to go, which will load your bags and take them to your outside transportation. They charge a flat rate of 15 EUR. Did not use them, as it was a short walk, but thought it was reasonable given that's what we normally tip someone when we elect baggage service.
Got to airport around 8:30 for the 13:05 flight for PHL. If you are flying American - they will not let you line up until 3 hours before. Security line wasn't bad - 15 minutes tops. It is quite a walk from the security to the gates. They have the US based flights at the far end of the terminal and a separate blocked off section where you go through passport control right before your gate.