Final question:
Should I reserve the Alsa bus to Lisbon Oriente or Lisbon Sete Ríos if I want to be near the airport? There are two choices.
And the bus will stop there before Sete Rios.
The bus station in SdC is easily reached by city bus and recommended since it's a bit out from the cathedral area. There are a surprising number of people going to Portugal so yes, you should reserve,