Hi,
Climbing starts after Puebla de Sanabria, so you have some days of trainig before.
I can remember, that there was a very long and demanding ascent after Puebla de Sanabria (something similar to O´Cebreiro) and then a narrow path down to Lubián, but nothing terrific. For this purpose, next time I plan to stop in Requejo rather than in Puebla de Sanabria.
Lubián to A Gudina could be compared to Rabanal-Riego d'Ambros on Camino Francés.
Next day to Laza is also some hills and rather long, but still doable (my parents were 75 and 69 when they walked with me in 2010). The only steep downhill section is to Campobecerros, that could be compared to Riego d'Ambros to Molinaseca. But you can stay on the forrest track (recommended alternative route for cyclists) which is slightly longer.
Very good pilgrims menu in restaurante "A Picota" in Laza.
Next morning some climbing to Albergaría, but then you have earned a coffee and a bocadillo in "El Rincón de Peregrino".
The day out of Ourense we took the left route. It is rather steep at the beginning, but still ok in the early morning hours.
In the public albergue in Castro-Dózon there was the offer of a nearby Restaurant "Parillada Don Antonio" for a pilgrims menue. They fetched us by car. It was the best dinner we had on the whole camino.
Enjoy your camino
Alexandra