just to bring this full circle - and thanks to everyone who helped. i'll post a more full recap later, but with respect to eating around midnight, you can definitely be more than sated at midnight or so in san sebastian. from 11:30 or so, in the old quarter, at the very least casa gandarias and al fuego negro serve hot and cold pintxos, and gandarias has its restaurant open for full on sit down meal where you can order until midnight. i'd called them and made an 11:30 reservation for the night i was scheduled to arrive to make sure i had a table, and then by a stroke of luck and scheduling (and useful frequent flyer status) i managed to get myself in 2 hours earlier than i'd thought, allowing for a few pintxos before a real meal. it's worth noting that gandarias is open all night, with the kitchen ceasing to make hot food between midnight and 11am - but during off hours all sorts of cold pintxos, and hams, chorizo etc is available. no problem. this is especially useful for all of those from london who are of necessity flying in at off hours either to bilbao or biarritz and therefore get into san sebastian later in the evening. it's also useful since gandarias is one of the 3 or so best pintxo bars i went to. one final note: the drive to san sebastian from bilbao does take about 1 hour, but once you're there, if it's your first time, count on it being another 30 minutes to figure out how to get to your hotel. those one way streets are crazy. like i said, more later, but that's the answer to my original question.