Is a lot cooler than Lisbon, temperature wise, but should still be nice in Sept. I’d do a boat tour up the Douro. They rave about a local meal called Francesinha which is just a pile of bread with meats and an egg on top. Just a stodgy mess.
Can’t remember any good restaurants off the top of my head but there are plenty. There was a bar called Bar With Pool Table which showed sport on a stinking tele and had a pool table and was like a dirty barn. Recommended
Got rubbered on the port cellar tours which are interesting if you’re into it but a lot of people do them just cos it’s the done thing so I wouldn’t bother if you’re not into port or the process of making it.
Church of St Francis is worth a look around. Mainly for the mad skull and bones room.
Cheers pal, yeh port is a massive no-go for me, once filled a wine glass up with it and took a huge gulp as I thought it was red wine and wanted to die

Will check out the other spots. My mate will deffo want to do the river tour.