Ferragudo is 70kms from Faro... a bit far to go to get a train.
What you should do is catch the train from Portimão, a city the same size as Faro, and on the other side of the River Arade from Ferragudo.(3km)
You get a train from Portimão to Tunes Junction and connect there with the intercity alfapendular train from Faro to Porto via Lisbon.
If you go to my blog at:
http://barlaventostravelblog.blogspot.com/
Scroll down on the right hand panel until you come to the section entitled:
»» Algarve & Portugal - Travel Transport Links
You will find links to the Portuguese Railways Porto/Lisbon/Faro and Algarve Lines Train Timetables.
Given the time of year, I would recommend that you book your train tickets at Portimão Station at least 24 hours before.
