We have also used taxis as a means of transportation all over Barcelona. They are plentiful and are allowed to use bus lanes so they get you where you are going quickly.
I guess we'll know by Sunday as to the alternative. If I remember correctly, there have been times when Alexandria VA has hosted cruise ships. Wherever they go, they'll have to get a bunch of folks back to Baltimore.
We have sailed under the bridge a number of times. Often looks like only a few feet clearance. It looks like the container ship hit one of the concrete support structures. I don't think so, but wonder if there is an alternate port on the other side of the bridge (like near Annapolis and the Naval Academy).
I would talk to the private excursion folks about handling a cruise that gets in at 9am. I know a lot of people rent cars but based on what we saw, would prefer to leave the driving to someone else.