I’m not at Ohr Naava enough to tell you how many singles attend regularly but they definitely have events and programs geared for singles. You can check their schedule on their website and sign up for emails. I’m not sure about Sundays but generally Miss Chevi Garfinkel speaks on mondays and Rabbi Wallerstein on Wednesdays, with some exception here and there. The FJJ (available online) has a listing of shiurim.