As for what to do.
My son told me about this tour company. Runner Bean Tours. I went on their Gothic Quarter Walking tour and tomorrow l am going to their Gaudi Walking tour.
Their meeting time is also great with Barcelona as a port of call too since it is at11am and last about 2 1/2 hrs. Just right for a shore excursions. Their price is unbeatable for it is really free. (I have just been to a free tour that charged before the tour started early this year cruising in Norway) You only give them tips at the end.
During the tour l was shown some places l have been and more others l don’t know of. I even enjoyed those l had been for our guide pointed out a lot of details to see, the history and tales about the places. He made it so very interesting. He told us tips like visiting Churches for free in the morning and evening. I wish they would start more interesting tours and l will be back . Their meeting place is also convenient to cruiser in Placa Reial, not far from the port shuttle, walkable or take the metro.
l think l covered most of your questions and you can email me if you want to. amri638 @gmail.com