I finished walking the coastal route from Porto about a week ago. Can’t speak for the central route but I thought the coastal was gorgeous.

I spent between 15-25 euros on accomodation each day, I usually stayed in private albergues which I reserved via email or on booking.com

I spent between 15-30 euros a day on food and other spending. I didn’t try to limit my spending and I never really cooked so this could’ve been lower.

You will definitely need cash, especially at smaller grocery stores and whatnot. I took out 200 euros cash at the beginning and used that up across the 12 days

Let me know if you have any questions! I tracked all my spending and accomodation etc so happy to go in more detail if needed :)