En flânant dans ses petites rues et en regardant ses maisons de pêcheurs, on serait excusable de penser que Port-Grimaud est un ancien village typique...
Lequel, "which one," is the pronominal equivalent of the interrogative adjective quel, meaning that quel + noun can be replaced by lequel. It has different forms depending on the gender and number of the noun it replaces.
When talking about something that happened in the past, the correct verb tense isn't always enough - sometimes you need a temporal expression to state just when it happened. The most common French temporal expressions are depuis and il y a, and they are not interchangeable.