Sept-Îles can be considered the capital of the Côte-Nord; it is also its biggest and most vibrant city. The city is mostly built around the 138, the only road to get to and from Sept-Îles. Arnaud Street is the principal commercial street outside the 138. Your options for hostels in Sept-Îles are very limited, but you will be well located; is possible to go downtown by foot and explore the surroundings.
Outside of the town are a few beautiful beaches. They are all on the same strip of land but called different names -- Monaghan, Ferguson, Routhier, and Levesque are the best-known beaches. During the winter, activities like snowmobiling, cross-country skiing, and snowshoe trekking are very popular with the locals.
Further down road 138, scenic places like Moisie River and Manitou River are absolutely spectacular. Since this is a relatively small town (less than thirty thousand people), it is very difficult to go places without a car. Car rental services are widely available throughout the town.
The main local food is fresh seafood, but wild game is readily available. Most of the restaurants will offer regular Quebecois fast food -- poutine, hot dogs, hamburgers, and fries. However, most of them have local twists on provincial favourites, most of them including shrimp and lobster. There are a lot of bars playing country music, a few taverns and watering holes and one pub. Since tourists are fairly rare in this town, people are very welcoming and are usually curious about your business there.
While tensions between local Native Americans and Caucasians sometimes make the headlines, you don't need to worry about your personal security, since Sept-Îles is a very safe place at all times.