Hi, Michal,
I started several weeks after you did, but by then nearly all the albergues were open. The only one we saw that had not opened was a huge private albergue next to the monastery at Zenarruza (actually, I think the town's name is Bolibar). Sometimes the albergues open late -- the one in Gernika, for instance, only opened at 3 or 4 pm so we went to a pension -- but I think you'll find most open.
As far as prices of single accommodation, as you probably know, it's not often the case that a single room costs half the price of a double room. I was walking with a friend, and the range of prices we paid in private accommodations was from about 24 E for the two of us (for double room with shower in pension in El Peral and again in some godforsaken hamlet on the road a day's walk from Luarca) to a high of 60 or 70E for a hotel (Vetusta in Oviedo, Mar Del Sueve in Colunga). The rest were somewhere in between.
Not much I can tell you about the weather. For some reason we were extremely lucky -- people walking either a day or so ahead or behind us got tons of rain, as we learned in Santiago. We had one day of all rain and several others of occasional showers, but nothing like what others described. Maybe the lesson here is that if you feel like you're walking under a thunder cloud, stop a day or so and maybe you'll escape it.
Have you decided what you'll do in Villaviciosa -- go down to Oviedo and take the Primitivo or continue along the coast on the norte? That for us was a terribly hard decision. In the end, we stuck with the Norte (with a "loop" down to Oviedo and back up at Aviles), but I definitely want to walk the Primitivo. People who did said it was beautiful, and mostly off road and rural.
You're so lucky you won't be rushed. There are lots of places that just called out for an extra day of rest and relaxation. We spent an extra day in Llanes and Oviedo, but there were others competing for our attention! Buen camino to you, and I'm happy to try to answer any other questions. Laurie