Hi, Deepforest, I don't know if you've been poking around the forum much, but there are a few documents in the Resources section that I think will answer a lot of your questions. There is a guide from Lisbon to Porto, one from Porto to Santiago, and a short document on how to put together shorter stages out of Lisbon. All of these were done by forum members, so they aren't professional but they are done with a lot of camino love.
https://www.caminodesantiago.me/community/resources/categories/camino-portugues.40/
The numbers from Lisbon are really increasing, and I doubt that you and your friend will be alone. Probably no crowds, but I think you will find companionship. The kindness and friendliness of the Portuguese people will make you feel comfortable and at home. No language worries, almost all young people speak good English, it's pretty astonishing. Some of the towns are quite nice, the convent at Tomar is grand, the ruins at Conimbriga are pretty cool, the university city of Coimbra is well worth a visit. All in all, I think the caminho from Lisbon has a lot going for it -- if you search through the forum archives you can find lots of posts on that topic. Here's one I like, but there are lots more:
https://www.caminodesantiago.me/community/threads/why-start-in-lisbon.29651/
The number of albergues is increasing quickly -- when I walked in 2009 there were none, now there are lots. In fact, one opened less than two weeks ago, in Alpriate. It is about 20 km from the Lisbon cathedral, and is run by the Via Lusitana, the Lisbon Camino Association. They also have the most up to date listing of accommodations, IMO:
http://www.vialusitana.org/caminho-portugues/albergues/ (BUT.... They don't yet list their own Alpriate albergue!)
The Alpriate albergue is right on the camino, in a little town with a cafe where you will find cheap and decent home cooking. Definitely the place to stop on day 1!!!
Bom caminho, Laurie