Hello,
I'd like to address your possible itinerary.
I've been to Lisbon on three occasions, 1, 3 and 5 full days of sight seeing.
I have two books to recommend: RS's Portugal and the current Lisbon TimeOut book.
My trips, all three being different:
1) with husband and a 15 year old
2) colleged age daughter
and 3) with my sister.
Trip 1) was sights
2) and 3) had wine and port tastings and different neighborhoods.
2) and 3) also went to Porto via train. Bought tickets at the stations and had no problems.
Please PM (prrsonal message) me and I'd be happy to help.