Exactly what GregorMC said. I also did the CI this week despite heavy rain from Thursday - not too fun! Most of the lodgings and cafes on the route don't feel particularly pilgrim driven...especially as I've opted for private lodgings. So I have a feeling these places might be open for locals regardless. The Buen Camino app was very useful, but it takes a few tries to get used to the weird layout. Don't give up! Especially the variations are very good. Luckily I had very good cell reception most everywhere, so could always find my way with the help of the app, especially where yellow arrows failed on variations.
You don't have to carry too much water with you (fountains every 5km and they often list the distance to the next official fountain too!) but I would definitely carry ample snacks, especially for days 3 & 4, as I didn't find much food options. I was also very grateful for my 2 min noodles on 2 occasions, where I would arrive hungry at my lodgings at 4pm, but dinner wouldn't really be accessible until much later.