we took the metro from the airport to lapa station which is relatively a long ride but you can take the taxi it will cost about 20 euros.
luis is a really nice guy, he was always reachable, and always offering help and suggestions. he even booked a taxi for us to go back to the airport (at 4 a.m!) .
the haus was lovely, small but full of details with an artistic touch. it has a balcony where you can drink coffee and enjoy the sun and the flying seagulls, usually there is someone playing music on the street which makes staying there even better.

the location is near the center you can reach the super-market and the historical city in about 5 minutes walking. Down the street there is small Cafés where you can have breakfast for reasonable prices.
we really enjoyed our stay there and luis made us feel home i would definitely do it again if i ever find myself in Porto.
ps: check the weather before you book the flight :p