@PizzaPastaWine Firstly, I'm very jealous! Here are my tips based on my trip last year...
1 - work out where you want to eat in Porto before you go, and book! Lots of restaurants are very tiny, and they get booked up. So then you end up in the big touristy ones.
2 - visit a port house - we did Taylors, and it was great
3 - try a Porto Tonico. On your first day (so that you have plenty of time for more once you've realised how nice they are)
4 - get the tram to the sea, walk along the sea front, stopping at all the lovely beach bars for a drink/tapas
5 - do some kind of walking tour (a self guided one - doesn't need to be a group one). There are loads of interesting buildings/facts/things to see
6 - Make sure you know which station your train goes from. We just assumed it left from the main station in the city centre, but it didn't - it went from the one on the eastern side of town (a taxi ride away).
7 - Take a trip on the river once you get to your quinta. We stayed further inland than you, and went even further inland again from there. It was really interesting hearing all about the farming/agriculture etc from the boat commentary
8 - even if you do a port tasting in Porto, do another one where you stay inland. It was quite different hearing about it all from the farmer's perspective, and ours had plenty of wine to taste as well as port
9 - eat loads of Pastel de Nata
10 - Marvel at how (relatively) cheap it is to drink vs everywhere else I've been recently in Europe. Made a very pleasant change!