Another vague answer I'm afraid, it's hard to say. I have walked a few times during semana santa, the week leading up to Easter Sunday, including on the Norte. The majority of hospitality locations are open, and doing a booming business, but I recall some smaller places closing Easter Friday and Sunday. The real issue to consider is where you will be on those days, as it's a holiday weekend, and things book up. If I was in a tiny hamlet, some cafes may shut - in a larger city, the hostals may be full. I have always emailed ahead of time and booked places on Easter weekend. It wasn't clear to me that I had to, but you will definitely notice Spaniards travelling more that weekend. Getting food is not going to be an issue, there is always somewhere to eat open, but most shops will close on the Friday and the Sunday, so plan ahead for supplies. But walking into San Sebastion or Bilbao on Good Friday? You will find the lower cost accommodations booked out, and the higher priced places readily available....at a higher-still price.