It is not that complicated.
If you follow the waymarkers to Vila do Conde you'll arrive at the bridge over the river -the monastery is right in front of you on the top of a hill- and at the moment you have crossed this bridge, turn right and find your waymarkers . But be carefull. Directly after one meter there is a waymarker to the right.. following this you are lead underneath the bridge to the other side of the road and into the centro antigo of Vila doConde and the coastal route.
If yo want to go to São Pedro de Rates , you keep following the river , cross the metro line from Povoa da Varzím to Porto vv . And follow the yellow markers to São Pedro de Rates.
About the "confusing " names of the CP.
Starting in Lisbon direction Azambuja ,Santarèm, Tomar,Coimbra São João do Madeira to Porto you are on the Central route
Leaving Porto through the urbanised part to Vairão (direction Porto airport) and Vilarinho
you still are on the central route to São Pedro de Rates, Barcelos,
Casa da Fernanda Ponte de Lima and Valença do Minho into Spain.
Leaving Porto alongside the Douro river and Atlantic ocean coast (allways at your left side) to Matosinhas, Angeiras, Vila do Conde, Póvoa da Varzím, Esposende ,Vila do Conde, Via Praia de Ãncora and Caminha into Spain you are on the coastal Caminho Português.
Here and there on the coastal the path splits off .one follows the coastline ,the other goes into the hills but at times they come together.
Then there is a third caminho path ,far away from the two above mentioned ones., the caminho Português Interior. You have to travel to Coimbra in central Portugal to find the markers in the village of Farminhão ,north east of Coimbra.
It leads along the mountains of the Serra da Estrella (beautifull area to visit if you'll ever have the time) to Viseu, Lamego and Chaves into Spain where it hits the ruta de la Via de la Plata in Ourense on the way to Santiago.
There is excellent information about all this routes in the various subforums here on this forum.
And a look at a detailed map ( google earth or ios maps) learns you all about the places ,mentioned above and you'll understand all about the geography of Portugal and the caminho routes.
Bom caminho and happy new year 2017.