For this tour, go to the corner of the Rua de Sao Joao Novo and the Rua do Infante Dom Henrique. The departure stop of the bus tour is on the north side of the Rua do Infante Dom Henrique; buy the ticket from the driver, it's about 10 euros.
You can get off at a number of stops such as Rem Koolhaas' Casa da Musica (finished in 2005) which is located half way between the centre of Porto and the Atlantic coast. However, we decided just to enjoy the tour (see pictures below of some of the sites you pass), then got off at the ocean front for an hour's visit. The fort (name?) is worth a quick visit and should not cost more than a couple of euros.
After the ocean front visit, take the bus back into town and have a good meal in one of the restaurants on the Cais di Ribeira. Enjoy!
