Hey Soda, WELCOME TO THE BOARDS!
One of the TOP HOSTEL's in the world(voted by customers of Hostelworld) is right there in Madrid, called the Barbieri International
. No curfew and very much worth checking in to...
Also, Los Amigos Backpackers Hostel
is very laid back with NO curfew too.
Here's a list of other Hostels and info on Madrid
that may be useful to you.
Good luck B) !