Hi, Hel and Scott,
I think there have been a few new albergues opened north of Porto, but to my knowledge there are neither albergues nor plans for them south of Porto. The Lisbon to Porto segment is very solitary. I have been in contact with a woman who is right now reaching Spain. She began in Lisbon but soon got disheartened by the lack of walkers and lack of information, so she took a bus up to Porto.
When I walked last year, I didn't meet anyone till I got to Porto, and you're right that the route is mostly pavement. But there are a lot of very nice towns along the way and they all have inexpensive pension-type places (I think I've got them all, or most of them, in my online guide).
About the weather -- I have lived in Lisbon for two different years, 2004-05, and 2008-09. One November was dry and sunny (part of a drought), but last November it started to rain around Nov. 15 and didn't stop till March. I've heard from my friends there that this year has been the same. But maybe you'll get lucky.
One last thing -- none of the route I walked was on the coast. I think there is a secondary coastal route, and I have seen some random arrows in different towns along the coast of northern Portugal, but I always asked neighbors or shop people when I saw one and met no one who knew anything about the Camino.
Hope this helps. Laurie