I understand that if I take a train from Santiago to Porto that I will need to transfer at, or near the border of Spain and Portugal. I am a bit confused about the transfer point. In "Spain 2013", Rick mentions transferring at Vigo, or Redondela. The confusion that I have is that there are Renfe & DBahn listings for "Vigo-Guixar". Does anyone know if this last one is the actual transfer point, and is that the location I should plan for when purchasing tickets? Thank you
Vigo-Guixar is the correct station. You don't have to tell DB the connection points you prefer. If you search between your start and end city, if gives you a schedule with recommended connection points. Although connections on that route are still poor, they have changed a bit. The 7:30 a.m. departure (for my test date) has connections at Vigo and Valenca (with layover), or the 17:30 departure only changes at Vigo.
P.S. Portugal book researchers had their work cut out for them this summer. A few book updates are currently online at http://www.ricksteves.com/europe/portugal/guidebook-updates, but the book that comes out in March will have many more changes.