Hi Trekker13,
Welcome to the Forum.
There is a great deal of information available here if you go to the section on the Camino Portugues.
There are mixed views about the walk out of Oporto, I was one of those who opted to take the metro out of town, I then walked along the beach to Vila do Conde. Others have other views.
You get stamps in albergues, the Portuguese albergues are generally very nice though you sometimes have to search for a key! Some bars have stamps, though not so many, also the Guardia Civil and the Tourist Offices.
Enjoy your camino,
Sue