Where to Stay
Stay at 3 Ducks, Peace & Love or St. Christopher’s. They are all known for having good bars and they can get pretty wild at night.
Where to Party
Paris is definitely a challenging city for party backpackers. Drinks are ridiculously expensive and busy clubs can be hard to find if you don’t know any locals. However, there is a decent pub crawl (http://www.newparistours.com/daily-tours/new-paris-pub-crawl.html) that I would recommend doing early on in your trip so you can meet other travellers and get a good idea of where to go. Check out Rex Club, Batofar and Social Club. You can also find good after hours in Paris.
You can definitely hear some good music in Paris. Since it is a big major city, many international artists of all genres play concerts here. If you are into electronic music, check out listings on Resident Advisor as techno music is really popular here.
During the Day
Go up the Eiffel Tower, take a free walking tour, explore the Louvre museum (houses the Mona Lisa), check out the Notre Dame Cathedral, walk around Champs-Elysees, and eat French cuisine.