John Merrill did it clockwise as well. According to him going anti-clockwise was the devil's way. I think he was quite spiritual as he started and finished at St Paul's Cathedral, and if I recall correctly he met the lady who was to become his wife (Sheila?)in Scotland whilst recovering from a stress fracture.
Barcelona is a long way from St Sebastian and the GR11 doesn't go there. Easiest part of the section is from Hondarribia through Navarra. Nicest part is near Ordesa - a long way from either Barcelona or St Sebastian.
As the others have said it is now only a refuge shelter and only has 6 bunks (some info on the net is very dated). You will need a sleeping bag and a camp stove and in summer bring your own water as there is no spring. There used to be a warden, cooking facilities and a smalll bar up until a few years ago but now it is more of a mountain hut.
That said the location is spectacular.
For the other refuges a sleeping bag will suffice.