See my answer in the the other post of you!
The part from Lisbon is great-my wife and I walked from there in 2013.
last year we walked from Porto but the coatal part.
This year we did not walk but were hospitaleiros at casa Fernanda.
The Lisbon to Pirto is a nice part, especially from Santarèm so you could take the commutertrain from Lisbon to Santarèm and start from there and see nice places like Tomar with its Templars Convent.
The part from Porto is more "socialised". You will meet more pilgrims and you see a nice part of Portugal.
So my suggestion was. Start in Porto and walk via Barcelos en stay at Fernanda , walk the last part to Ponte de Lima and returm back to Lisbon by train to catch your flight.
A bit of a puzzle but you see a nice part of Partugal and the Portuguese caminho.
There is a fast train from Lisbon to Porto.
http://www.cp.pt/sites/passageiros/en/train-times/Train-time-results
Bom caminho.